chests: Do not hardcode "default:".

This allows other mods to greater use the default.chest functions.

Fixes https://github.com/minetest/minetest_game/issues/1936

v2: Keep the default formspec name.
v3: Remove unnecessary backwards compatibility.
v4: register_lbm only applies to "default:chest" and
    "default:chest_locked".

mods/default/chests.lua

@@ -44,7 +44,7 @@ function default.chest.chest_lid_close(pn)
 	end
 
 	local node = minetest.get_node(pos)
-	minetest.after(0.2, minetest.swap_node, pos, { name = "default:" .. swap,
+	minetest.after(0.2, minetest.swap_node, pos, { name = swap,
 			param2 = node.param2 })
 	minetest.sound_play(sound, {gain = 0.3, pos = pos,
 		max_hear_distance = 10}, true)
@@ -132,7 +132,7 @@ function default.chest.register_chest(name, d)
 					pos = pos, max_hear_distance = 10}, true)
 			if not default.chest.chest_lid_obstructed(pos) then
 				minetest.swap_node(pos,
-						{ name = "default:" .. name .. "_open",
+						{ name = name .. "_open",
 						param2 = node.param2 })
 			end
 			minetest.after(0.2, minetest.show_formspec,
@@ -203,7 +203,7 @@ function default.chest.register_chest(name, d)
 					max_hear_distance = 10}, true)
 			if not default.chest.chest_lid_obstructed(pos) then
 				minetest.swap_node(pos, {
-						name = "default:" .. name .. "_open",
+						name = name .. "_open",
 						param2 = node.param2 })
 			end
 			minetest.after(0.2, minetest.show_formspec,
@@ -215,7 +215,7 @@ function default.chest.register_chest(name, d)
 		def.on_blast = function(pos)
 			local drops = {}
 			default.get_inventory_drops(pos, "main", drops)
-			drops[#drops+1] = "default:" .. name
+			drops[#drops+1] = name
 			minetest.remove_node(pos)
 			return drops
 		end
@@ -248,7 +248,7 @@ function default.chest.register_chest(name, d)
 			def_opened.tiles[i].backface_culling = true
 		end
 	end
-	def_opened.drop = "default:" .. name
+	def_opened.drop = name
 	def_opened.groups.not_in_creative_inventory = 1
 	def_opened.selection_box = {
 		type = "fixed",
@@ -265,29 +265,32 @@ function default.chest.register_chest(name, d)
 	def_closed.tiles[5] = def.tiles[3] -- drawtype to make them match the mesh
 	def_closed.tiles[3] = def.tiles[3].."^[transformFX"
 
-	minetest.register_node("default:" .. name, def_closed)
+	minetest.register_node(name, def_closed)
-	minetest.register_node("default:" .. name .. "_open", def_opened)
+	minetest.register_node(name .. "_open", def_opened)
 
 	-- convert old chests to this new variant
-	minetest.register_lbm({
+	if name == "default:chest" or name == "default:chest_locked" then
-		label = "update chests to opening chests",
+		local itemname = string.match(name, ":(.*)")
-		name = "default:upgrade_" .. name .. "_v2",
+		minetest.register_lbm({
-		nodenames = {"default:" .. name},
+			label = "update chests to opening chests",
-		action = function(pos, node)
+			name = "default:upgrade_" .. itemname .. "_v2",
-			local meta = minetest.get_meta(pos)
+			nodenames = {name},
-			meta:set_string("formspec", nil)
+			action = function(pos, node)
-			local inv = meta:get_inventory()
+				local meta = minetest.get_meta(pos)
-			local list = inv:get_list("default:chest")
+				meta:set_string("formspec", nil)
-			if list then
+				local inv = meta:get_inventory()
-				inv:set_size("main", 8*4)
+				local list = inv:get_list("default:chest")
-				inv:set_list("main", list)
+				if list then
-				inv:set_list("default:chest", nil)
+					inv:set_size("main", 8*4)
+					inv:set_list("main", list)
+					inv:set_list("default:chest", nil)
+				end
 			end
-		end
+		})
-	})
+	end
 end
 
-default.chest.register_chest("chest", {
+default.chest.register_chest("default:chest", {
 	description = S("Chest"),
 	tiles = {
 		"default_chest_top.png",
@@ -303,7 +306,7 @@ default.chest.register_chest("chest", {
 	groups = {choppy = 2, oddly_breakable_by_hand = 2},
 })
 
-default.chest.register_chest("chest_locked", {
+default.chest.register_chest("default:chest_locked", {
 	description = S("Locked Chest"),
 	tiles = {
 		"default_chest_top.png",