diff --git a/.luacheckrc b/.luacheckrc
index 2933f30..459b2e2 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -1,17 +1,30 @@
+std = "lua51+minetest"
 unused_args = false
 allow_defined_top = true
+max_line_length = 999
+max_comment_line_length = 999
 
-read_globals = {
-	"DIR_DELIM",
-	"minetest", "core",
-	"dump",
-	"vector", "nodeupdate",
-	"VoxelManip", "VoxelArea",
-	"PseudoRandom", "ItemStack",
-	"intllib",
-	"default",
-	table = { fields = { "copy", "getn" } },
-	"biome_lib",
-	"stairs", "stairsplus",
+stds.minetest = {
+	read_globals = {
+		"minetest",
+		"vector",
+		"VoxelManip",
+		"VoxelArea",
+		"PseudoRandom",
+		"ItemStack",
+		"default",
+		table = {
+			fields = {
+				"copy",
+			},
+		},
+		"dump",
+	}
 }
 
+read_globals = {
+	"biome_lib",
+	"stairsplus",
+	"stairs",
+	"doors",
+}
diff --git a/cocos_palm.lua b/cocos_palm.lua
index 391819b..d8273b5 100644
--- a/cocos_palm.lua
+++ b/cocos_palm.lua
@@ -23,7 +23,11 @@ end
 ftrunk.drop = "moretrees:palm_trunk"
 gftrunk.drop = "moretrees:palm_trunk"
 ftrunk.after_destruct = function(pos, oldnode)
-	local coconuts = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, {"group:moretrees_coconut"})
+	local coconuts = minetest.find_nodes_in_area(
+		{x=pos.x-1, y=pos.y, z=pos.z-1},
+		{x=pos.x+1, y=pos.y, z=pos.z+1},
+		{"group:moretrees_coconut"}
+	)
 	for _,coconutpos in pairs(coconuts) do
 		-- minetest.dig_node(coconutpos) does not cause nearby coconuts to be dropped :-( ...
 		--minetest.dig_node(coconutpos)
@@ -46,7 +50,11 @@ local coconut_regrow_abm_spec = {
 	interval = moretrees.coconut_flower_interval,
 	chance = moretrees.coconut_flower_chance,
 	action = function(pos, node, active_object_count, active_object_count_wider)
-		local coconuts = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, "group:moretrees_coconut")
+		local coconuts = minetest.find_nodes_in_area(
+			{x=pos.x-1, y=pos.y, z=pos.z-1},
+			{x=pos.x+1, y=pos.y, z=pos.z+1},
+			"group:moretrees_coconut"
+		)
 		-- Expected growth interval increases exponentially with number of coconuts already hanging.
 		-- Also: if more coconuts are hanging, the chance of picking an empty spot decreases as well...
 		if math.random(2^#coconuts) <= 2 then
@@ -76,15 +84,18 @@ minetest.register_abm({
 	chance = 1,
 	action = function(pos, node, active_object_count, active_object_count_wider)
 		minetest.swap_node(pos, {name="moretrees:palm_fruit_trunk"})
-		local poslist = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, "air")
+		local poslist = minetest.find_nodes_in_area(
+			{x=pos.x-1, y=pos.y, z=pos.z-1},
+			{x=pos.x+1, y=pos.y, z=pos.z+1},
+			"air"
+		)
 		local genlist = {}
 		for k,v in pairs(poslist) do
 			genlist[k] = {x = math.random(100), pos = v}
 		end
 		table.sort(genlist, function(a, b) return a.x < b.x; end)
-		local gen
 		local count = 0
-		for _,gen in pairs(genlist) do
+		for _, gen in pairs(genlist) do
 			minetest.swap_node(gen.pos, {name = "moretrees:coconut_3"})
 			count = count + 1
 			if count == 4 then
@@ -109,7 +120,8 @@ local coconut_growfn = function(pos, elapsed)
 		-- Drop coconuts (i.e. remove them), so that new coconuts can grow.
 		-- Coconuts will drop as items with a small chance
 		if math.random(coconut_drop_ichance) == 1 then
-			if moretrees.coconut_item_drop_ichance > 0 and math.random(moretrees.coconut_item_drop_ichance) == 1 then
+			if moretrees.coconut_item_drop_ichance > 0
+				and math.random(moretrees.coconut_item_drop_ichance) == 1 then
 				local items = minetest.get_node_drops(minetest.get_node(pos).name)
 				for _, itemname in pairs(items) do
 					minetest.add_item(pos, itemname)
@@ -190,55 +202,95 @@ if moretrees.coconuts_convert_existing_palms then
 			local leaves
 			local coconuts
 			-- One regular trunk must be adjacent to  the coconut
-			trunks = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, "moretrees:palm_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=pos.x-1, y=pos.y, z=pos.z-1},
+				{x=pos.x+1, y=pos.y, z=pos.z+1},
+				"moretrees:palm_trunk"
+			)
 			if #trunks ~= 1 then
 				return
 			end
 			local tpos = trunks[1]
 			-- 1 or 2 other trunks must be one level below to the trunk being converted.
-			trunks = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y-1, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y-1, z=tpos.z+1}, "moretrees:palm_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y-1, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y-1, z=tpos.z+1},
+				"moretrees:palm_trunk"
+			)
 			if #trunks < 1 or #trunks > 2 then
 				return
 			end
 			-- 1 or 2 other trunks must be two levels below to the trunk being converted.
-			trunks = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y-2, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y-2, z=tpos.z+1}, "moretrees:palm_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y-2, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y-2, z=tpos.z+1},
+				"moretrees:palm_trunk"
+			)
 			if #trunks < 1 or #trunks > 2 then
 				return
 			end
 			-- 1 or 2 trunks must at the level of the trunk being converted.
-			cvtrunks = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y, z=tpos.z+1}, "moretrees:palm_trunk")
+			cvtrunks = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y, z=tpos.z+1},
+				"moretrees:palm_trunk"
+			)
 			if #cvtrunks < 1 or #cvtrunks > 2 then
 				return
 			end
 			-- No trunks may be one level above the trunk being converted.
-			trunks = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y+1, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y+1, z=tpos.z+1}, "moretrees:palm_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y+1, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y+1, z=tpos.z+1},
+				"moretrees:palm_trunk"
+			)
 			if #trunks ~= 0 then
 				return
 			end
 			-- Leaves must be one level above the trunk being converted.
-			leaves = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y+1, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y+1, z=tpos.z+1}, "moretrees:palm_leaves")
+			leaves = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y+1, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y+1, z=tpos.z+1},
+				"moretrees:palm_leaves"
+			)
 			if #leaves == 0 then
 				return
 			end
 			-- Leaves must be two levels above the trunk being converted.
-			leaves = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y+2, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y+2, z=tpos.z+1}, "moretrees:palm_leaves")
+			leaves = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y+2, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y+2, z=tpos.z+1},
+				"moretrees:palm_leaves"
+			)
 			if #leaves == 0 then
 				return
 			end
 			-- No cocos fruit trunk may already be adjacent to the coconut
-			trunks = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, "moretrees:palm_fruit_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=pos.x-1, y=pos.y, z=pos.z-1},
+				{x=pos.x+1, y=pos.y, z=pos.z+1},
+				"moretrees:palm_fruit_trunk"
+			)
 			if #trunks ~= 0 then
 				return
 			end
 			-- No cocos fruit trunk may be adjacent to or below the trunk being converted.
-			trunks = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y-2, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y, z=tpos.z+1}, "moretrees:palm_fruit_trunk")
+			trunks = minetest.find_nodes_in_area(
+				{x=tpos.x-1, y=tpos.y-2, z=tpos.z-1},
+				{x=tpos.x+1, y=tpos.y, z=tpos.z+1},
+				"moretrees:palm_fruit_trunk"
+			)
 			if #trunks ~= 0 then
 				return
 			end
 			-- Convert trunk and all coconuts nearby. Maybe convert 2 trunks, just in case...
-			for _, tpos in pairs(cvtrunks) do
-				minetest.swap_node(tpos, {name = "moretrees:palm_fruit_trunk"})
-				coconuts = minetest.find_nodes_in_area({x=tpos.x-1, y=tpos.y, z=tpos.z-1}, {x=tpos.x+1, y=tpos.y, z=tpos.z+1}, "moretrees:coconut")
+			for _, tpos_1 in pairs(cvtrunks) do
+				minetest.swap_node(tpos_1, {name = "moretrees:palm_fruit_trunk"})
+				coconuts = minetest.find_nodes_in_area(
+					{x=tpos_1.x-1, y=tpos_1.y, z=tpos_1.z-1},
+					{x=tpos_1.x+1, y=tpos_1.y, z=tpos_1.z+1},
+					"moretrees:coconut"
+				)
 				for _, coconutpos in pairs(coconuts) do
 					minetest.swap_node(coconutpos, {name = "moretrees:coconut_3"})
 				end
diff --git a/date_palm.lua b/date_palm.lua
index be694a9..4de81f0 100644
--- a/date_palm.lua
+++ b/date_palm.lua
@@ -44,7 +44,11 @@ for k,v in pairs(trunk.tiles) do
 end
 ftrunk.drop = "moretrees:date_palm_trunk"
 ftrunk.after_destruct = function(pos, oldnode)
-	local dates = minetest.find_nodes_in_area({x=pos.x-2, y=pos.y, z=pos.z-2}, {x=pos.x+2, y=pos.y, z=pos.z+2}, {"group:moretrees_dates"})
+	local dates = minetest.find_nodes_in_area(
+		{x=pos.x-2, y=pos.y, z=pos.z-2},
+		{x=pos.x+2, y=pos.y, z=pos.z+2},
+		{"group:moretrees_dates"}
+	)
 	for _,datespos in pairs(dates) do
 		-- minetest.dig_node(datespos) does not cause nearby dates to be dropped :-( ...
 		local items = minetest.get_node_drops(minetest.get_node(datespos).name)
@@ -120,8 +124,11 @@ minetest.register_abm({
 			type = "m"
 			minetest.swap_node(pos, {name="moretrees:date_palm_mfruit_trunk"})
 		end
-		local dates1 = minetest.find_nodes_in_area({x=pos.x-1, y=pos.y, z=pos.z-1}, {x=pos.x+1, y=pos.y, z=pos.z+1}, "air")
-		local genpos
+		local dates1 = minetest.find_nodes_in_area(
+			{x=pos.x-1, y=pos.y, z=pos.z-1},
+			{x=pos.x+1, y=pos.y, z=pos.z+1},
+			"air"
+		)
 		for _,genpos in pairs(dates1) do
 			if math.random(100) <= 20 then
 				if type == "m" then
@@ -131,7 +138,11 @@ minetest.register_abm({
 				end
 			end
 		end
-		local dates2 = minetest.find_nodes_in_area({x=pos.x-2, y=pos.y, z=pos.z-2}, {x=pos.x+2, y=pos.y, z=pos.z+2}, "air")
+		local dates2 = minetest.find_nodes_in_area(
+			{x=pos.x-2, y=pos.y, z=pos.z-2},
+			{x=pos.x+2, y=pos.y, z=pos.z+2},
+			"air"
+		)
 		for _,genpos in pairs(dates2) do
 			if math.random(100) <= 5 then
 				if type == "m" then
@@ -195,7 +206,7 @@ local function find_fruit_trunks_near(ftpos, sect)
 	local r = moretrees.dates_pollination_distance + 2 * math.sqrt(2)
 	local sect_hr = math.floor(r / 3 + 0.9999)
 	local sect_vr = math.floor(r / 2 + 0.9999)
-	local t0us = core.get_us_time()
+	local t0us = minetest.get_us_time()
 	local t0s = os.time()
 
 	-- Compute elapsed time since last search.
@@ -266,7 +277,7 @@ local function find_fruit_trunks_near(ftpos, sect)
 	end
 
 	-- Update search statistics
-	local t1us = core.get_us_time()
+	local t1us = minetest.get_us_time()
 	if t1us < t0us then
 		-- Wraparound. Assume the search lasted less than 2^32 microseconds (~71 min)
 		-- (so no need to apply another correction)
@@ -306,7 +317,7 @@ minetest.register_chatcommand("dates_stats", {
 	params = "|chat|log|reset",
 	privs = { server = true },
 	func = function(name, param)
-		param = string.lower(string.trim(param))
+		param = string.lower(param:gsub("%s+", ""))
 		if param == "" or param == "chat" then
 			return dates_print_search_stats(false)
 		elseif param == "log" then
@@ -526,7 +537,6 @@ end
 local dates_growfn = function(pos, elapsed)
 	local node = minetest.get_node(pos)
 	local delay = moretrees.dates_grow_interval
-	local r = moretrees.dates_pollination_distance
 	local action
 	if not node then
 		return
@@ -594,15 +604,16 @@ local dates_growfn = function(pos, elapsed)
 	return action
 end
 
+--[[
 -- Alternate growth function for dates.
 -- It calls the primary growth function, but also measures CPU time consumed.
 -- Use this function to analyze date growing performance.
 local stat = {}
 stat.count = 0
 local dates_growfn_profiling = function(pos, elapsed)
-	local t0 = core.get_us_time()
+	local t0 = minetest.get_us_time()
 	local action = dates_growfn(pos, elapsed)
-	local t1 = core.get_us_time()
+	local t1 = minetest.get_us_time()
 	if t1 < t0 then
 		t1 = t1 + 2^32
 	end
@@ -656,6 +667,7 @@ local dates_growfn_profiling = function(pos, elapsed)
 			"TOTAL", count, sum/count))
 	end
 end
+--]]
 
 -- Register dates
 
diff --git a/depends.txt b/depends.txt
deleted file mode 100644
index 1636685..0000000
--- a/depends.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-default
-biome_lib
-vessels
-doors?
-stairs?
-moreblocks?
-intllib?
-farming?
-
diff --git a/description.txt b/description.txt
deleted file mode 100644
index 7c86723..0000000
--- a/description.txt
+++ /dev/null
@@ -1 +0,0 @@
-This mod adds a whole bunch of new types of trees to the game
diff --git a/mod.conf b/mod.conf
index fe9eac5..da7e493 100644
--- a/mod.conf
+++ b/mod.conf
@@ -1,4 +1,4 @@
 name = moretrees
 depends = default, biome_lib, vessels
-optional_depends = doors, stairs, moreblocks, intllib, farming
+optional_depends = doors, stairs, moreblocks, farming
 min_minetest_version = 5.2.0
diff --git a/node_defs.lua b/node_defs.lua
index 0fbec2c..4cf6f75 100644
--- a/node_defs.lua
+++ b/node_defs.lua
@@ -327,7 +327,7 @@ for i in ipairs(moretrees.treelist) do
 		chance = 1,
 		action = function(pos, node, active_object_count, active_object_count_wider)
 			local fdir = node.param2 or 0
-				nfdir = dirs2[fdir+1]
+				local nfdir = dirs2[fdir+1]
 			minetest.add_node(pos, {name = "moretrees:"..treename.."_trunk", param2 = nfdir})
 		end,
 	})
@@ -490,7 +490,6 @@ minetest.register_node("moretrees:rubber_tree_trunk_empty", {
 		"moretrees_rubber_tree_trunk_top.png",
 		"moretrees_rubber_tree_trunk_empty.png"
 	},
-	is_ground_content = true,
 	groups = {tree=1,snappy=1,choppy=2,oddly_breakable_by_hand=1,flammable=2},
 	sounds = default.node_sound_wood_defaults(),
 	paramtype2 = "facedir",
@@ -504,7 +503,7 @@ minetest.register_abm({
 	chance = 1,
 	action = function(pos, node, active_object_count, active_object_count_wider)
 		local fdir = node.param2 or 0
-			nfdir = dirs2[fdir+1]
+			local nfdir = dirs2[fdir+1]
 		minetest.add_node(pos, {name = "moretrees:rubber_tree_trunk_empty", param2 = nfdir})
 	end,
 })
diff --git a/screenshot.lua b/screenshot.lua
index cb2ad7a..28a8c25 100644
--- a/screenshot.lua
+++ b/screenshot.lua
@@ -31,7 +31,7 @@ index 8189ffd..afd4644 100644
 @@ -225,9 +225,12 @@ moretrees.ct_rules_b1 = "[-FBf][+FBf]"
  moretrees.ct_rules_a2 = "FF[FF][&&-FBF][&&+FBF][&&---FBF][&&+++FBF]F/A"
  moretrees.ct_rules_b2 = "[-fB][+fB]"
- 
+
 +local jleaves = 1
  function moretrees.grow_jungletree(pos)
         local r1 = math.random(2)
@@ -40,11 +40,11 @@ index 8189ffd..afd4644 100644
 +       jleaves = jleaves % 2 + 1
         if r1 == 1 then
                 moretrees.jungletree_model.leaves2 = "moretrees:jungletree_leaves_red"
-        else 
+        else
 @@ -235,6 +238,7 @@ function moretrees.grow_jungletree(pos)
         end
         moretrees.jungletree_model.leaves2_chance = math.random(25, 75)
- 
+
 +       r2=3
         if r2 == 1 then
                 moretrees.jungletree_model.trunk_type = "single"
@@ -62,7 +62,7 @@ minetest.register_chatcommand("make-scene", {
 		minetest.place_node({x=780, y=30, z=-276}, {name="default:obsidian"})
 
 		for z = -360, -300 do
-			dy=2
+			local dy=2
 			for x = 630 + (-z - 360)/3, 660 + (-z - 300)/3 do
 				for y = 5, 22 do
 					minetest.place_node({x=x, y=y, z=z}, {name="default:desert_stone"})
diff --git a/tree_models.lua b/tree_models.lua
index 879a32a..eb6541e 100644
--- a/tree_models.lua
+++ b/tree_models.lua
@@ -49,7 +49,6 @@ moretrees.poplar_model={
 	rules_b="[[T]&&G++f++ff++ff++ff++f--]G",
 	rules_c="[[T]&&G++f++ff++ff++ff++f--G++[d]G[d]G++G[d]G[d]G[d]G++G[d]G[d]G[d]G++G[d]G[d]G[d]G++G[d]G]G",
 	rules_d="f",
-	trunk="air",
 	trunk="moretrees:poplar_trunk",
 	leaves="moretrees:poplar_leaves",
 	angle=45,