Remove the txp_* overlay image feature

- For inventory and wield images, this is already
  possible via override.txt since 5.3.
- For special tiles, this will be possible in 5.4.
- This complicates things, and introduces warning
  messages into mods built without awareness of
  this feaure.
- As far as I know, no texture packs have actually
  ever used this feature.

mods/nc_api/init.lua

@@ -125,5 +125,4 @@ include("item_nodebox_zfighting")
 include("item_virtual")
 include("item_stackmax")
 include("item_touch_hurt")
-include("item_txp_overlay")
 include("item_tiledump")

mods/nc_api/item_txp_overlay.lua

@@ -1,58 +0,0 @@
--- LUALOCALS < ---------------------------------------------------------
-local io, minetest, nodecore, pairs, table, tostring, type
-    = io, minetest, nodecore, pairs, table, tostring, type
-local io_open, table_concat, table_sort
-    = io.open, table.concat, table.sort
--- LUALOCALS > ---------------------------------------------------------
-
-local missing = {}
-
-minetest.after(0, function()
-		local t = {}
-		for k in pairs(missing) do t[#t + 1] = k end
-		if #t < 1 then
-			return nodecore.log("action", "txp override images ok")
-		end
-		table_sort(t)
-		nodecore.log("warning", "missing txp override images:\n\t"
-			.. table_concat(t, "\n\t"))
-	end)
-
-local function overlay(name, img, imgtype, force)
-	if type(img) == "table" then
-		local t = {}
-		for k, v in pairs(img) do
-			if type(k) == "number" then
-				t[k] = overlay(name, v, imgtype .. tostring(k), force)
-			elseif k == "name" then
-				t[k] = overlay(name, v, imgtype, force)
-			else
-				t[k] = v
-			end
-		end
-		return t
-	end
-
-	if (not img) or (img == "") or (type(img) ~= "string")
-	or (not (force or img:match("%^"))) or img:match("%^txp_") then return img end
-
-	local tpath = "txp_" .. name:gsub("^%W+", "")
-	:gsub("%W+", "_") .. "_" .. imgtype .. ".png"
-
-	local fullpath = minetest.get_modpath(minetest.get_current_modname())
-	.. "/textures/" .. tpath
-	local f = io_open(fullpath, "rb")
-	if not f then
-		missing[fullpath] = img
-		return img
-	end
-	f:close()
-
-	return tostring(nodecore.tmod(img):add(tpath):makealpha(255, 254, 2))
-end
-
-nodecore.register_on_register_item(function(name, def)
-		def.inventory_image = overlay(name, def.inventory_image, "inv")
-		def.wield_image = overlay(name, def.wield_image, "wield")
-		def.special_tiles = overlay(name, def.special_tiles, "special", true)
-	end)