Modpack refactor (#4)

Split this mod into a set of sub-mods in a modpack, and in the process did a whole bunch of renovations.

* updated Subterrane's API to allow for more patterned placement of things
* added "warrens"
* clean separation of flooded and non-flooded caverns
* rearranged biomes to make cavern layers more distinct
* added oil layer
* added underworld layer

df_farming/pig_tail.lua

@@ -0,0 +1,117 @@
+-- internationalization boilerplate
+local MP = minetest.get_modpath(minetest.get_current_modname())
+local S, NS = dofile(MP.."/intllib.lua")
+
+local pig_tail_grow_time = df_farming.config.plant_growth_time * df_farming.config.pig_tail_delay_multiplier / 8
+
+local register_pig_tail = function(number)
+	local name = "df_farming:pig_tail_"..tostring(number)
+	local def = {
+		description = S("Pig Tail"),
+		_doc_items_longdesc = df_farming.doc.pig_tail_desc,
+		_doc_items_usagehelp = df_farming.doc.pig_tail_usage,
+		drawtype = "plantlike",
+		paramtype2 = "meshoptions",
+		place_param2 = 3,
+		tiles = {"dfcaverns_pig_tail_"..tostring(number)..".png"},
+		inventory_image = "dfcaverns_pig_tail_"..tostring(number)..".png",
+		paramtype = "light",
+		walkable = false,
+		floodable = true,
+		buildable_to = true,
+		groups = {snappy = 3, flammable = 2, plant = 1, not_in_creative_inventory = 1, attached_node = 1, light_sensitive_fungus = 11},
+		sounds = default.node_sound_leaves_defaults(),
+		
+		on_timer = function(pos, elapsed)
+			df_farming.grow_underground_plant(pos, name, elapsed)
+		end,
+		
+		drop = {
+			max_items = 1,
+			items = {
+				{
+					items = {'df_farming:pig_tail_seed 2', 'df_farming:pig_tail_thread 2'},
+					rarity = 9-number,
+				},
+				{
+					items = {'df_farming:pig_tail_seed 1', 'df_farming:pig_tail_thread'},
+					rarity = 9-number,
+				},
+				{
+					items = {'df_farming:pig_tail_seed'},
+					rarity = 9-number,
+				},
+			},
+		},
+	}
+	
+	if number < 8 then
+		def._dfcaverns_next_stage_time = pig_tail_grow_time
+		def._dfcaverns_next_stage = "df_farming:pig_tail_"..tostring(number+1)
+	end
+	
+	minetest.register_node(name, def)
+end
+
+for i = 1,8 do
+	register_pig_tail(i)
+end
+
+local place_list = {
+	minetest.get_content_id("df_farming:pig_tail_1"),
+	minetest.get_content_id("df_farming:pig_tail_2"),
+	minetest.get_content_id("df_farming:pig_tail_3"),
+	minetest.get_content_id("df_farming:pig_tail_4"),
+	minetest.get_content_id("df_farming:pig_tail_5"),
+	minetest.get_content_id("df_farming:pig_tail_6"),
+	minetest.get_content_id("df_farming:pig_tail_7"),
+	minetest.get_content_id("df_farming:pig_tail_8"),
+}
+-- doesn't set the timer running, so plants placed by this method won't grow
+df_farming.spawn_pig_tail_vm = function(vi, area, data, param2_data)
+	data[vi] = place_list[math.random(1,8)]
+	param2_data[vi] = 3
+end
+
+df_farming.register_seed(
+	"pig_tail_seed",
+	S("Pig Tail Spore"),
+	"dfcaverns_pig_tail_seed.png",
+	"df_farming:pig_tail_1",
+	pig_tail_grow_time,
+	df_farming.doc.pig_tail_desc,
+	df_farming.doc.pig_tail_usage)
+
+minetest.register_craftitem("df_farming:pig_tail_thread", {
+	description = S("Pig tail thread"),
+	_doc_items_longdesc = df_farming.doc.pig_tail_thread_desc,
+	_doc_items_usagehelp = df_farming.doc.pig_tail_thread_usage,
+	inventory_image = "dfcaverns_pig_tail_thread.png",
+	groups = {flammable = 1, thread = 1},
+})
+
+if minetest.get_modpath("wool") then
+	minetest.register_craft({
+		output = "wool:white",
+		recipe = {
+			{"group:thread", "group:thread"},
+			{"group:thread", "group:thread"},
+		}
+	})
+end
+if minetest.get_modpath("farming") then
+	minetest.register_craft({
+		output = "farming:string 2",
+		recipe = {
+			{"group:thread"},
+			{"group:thread"},
+		}
+	})
+end
+
+minetest.register_craft({
+	type = "fuel",
+	recipe = "df_farming:pig_tail_thread",
+	burntime = 1,
+})
+