Small stuff (#8)

* cave pearls and spindleshrooms (name subject to change) now are things. Not in mapgen yet.

* add the wandering "gas wisp" to light up some of the gas-filled caverns

* make wisps rarely spawned by gas explosions

* revamp spindlestems into a sort of mineral detector, add glowing extract bottles

* optimize pngs

* add gas wisps to mapgen

* add spindlestems to cavern level 1, most level 1 warrens are now lit up

* update internal names, adjust mineral detection range

* add cave pearls to some level 2 warrens and tunnels

* switch experimental simplecrafting_lib support to crafting mod

* Pearls don't grow on falling nodes

* put spindlestems with goblin caps, make them always grow red when near those

* bunch of documentation

* add castle coral to replace cave coral, which has been repurposed into column decoration

* documentation for cave coral, update some locale text

* add a recipe for cooking oil into paraffin

* add old bones to the underworld

* MIT license for bones_loot

* also cook black cap gills into paraffin, they're oily

* add salt crystals to the bloodthorn caverns, illuminating the floor

* documentation for salt crystals

* auto-generate minetestmapper colors.

need to update the spindlestem colours manually

* add spindlestem to fungiwood caverns too, and increase warren coverage

* in anticipation of eventually adding stuff below the Slade, making glowing pit erosion self-limiting.

* add a bit of displacement to the underside of the slade layer

* Unique images and names for cooking recipes.

* revamp bones loot

* add softer footsteps for some fungus types

* update mapgen_helper

* update cave coral screenshot

* mention glowing salts in bloodthorn caverns

df_underworld_items/glowing_pit_plasma.lua

@@ -138,9 +138,18 @@ if df_underworld_items.config.destructive_pit_plasma then
 				for y = pos.y-1, pos.y+1 do
 					for z = pos.z-1, pos.z+1 do
 						local test_pos = {x=x, y=y, z=z}
-						if minetest.get_item_group(minetest.get_node(test_pos).name, "pit_plasma_resistant") == 0 then
+						local node_name = minetest.get_node(test_pos).name
+						if minetest.get_item_group(node_name, "pit_plasma_resistant") == 0 then
 							sparkle_pos = test_pos
-							minetest.set_node(test_pos, {name="air"})
+							if minetest.get_item_group(node_name, "stone") > 0 then
+								if math.random() < 0.66 then
+									minetest.set_node(test_pos, {name="df_underworld_items:glow_amethyst"})
+								else
+									minetest.set_node(test_pos, {name="default:lava_source"})
+								end
+							else
+								minetest.set_node(test_pos, {name="air"})
+							end
 						end
 					end
 				end

df_underworld_items/mod.conf

@@ -1 +1,4 @@
-name = df_underworld_items
+name = df_underworld_items
+description = Various node types used by the dfcaverns mapgen mod for its underworld layer.
+depends = default, stairs
+optional_depends = intllib, doc, radiant_damage, mesecons_mvps, tnt