Replace GUI image texts with translatable labels

mods/ITEMS/mcl_furnaces/init.lua

@@ -9,8 +9,10 @@ local function active_formspec(fuel_percent, item_percent)
 	return "size[9,8.75]"..
 	"background[-0.19,-0.25;9.41,9.49;crafting_inventory_furnace.png]"..
 	mcl_vars.inventory_header..
+	"label[0,4;"..minetest.formspec_escape(minetest.colorize("#313131", S("Inventory"))).."]"..
 	"list[current_player;main;0,4.5;9,3;9]"..
 	"list[current_player;main;0,7.74;9,1;]"..
+	"label[2.75,0;"..minetest.formspec_escape(minetest.colorize("#313131", S("Furnace"))).."]"..
 	"list[current_name;src;2.75,0.5;1,1;]"..
 	"list[current_name;fuel;2.75,2.5;1,1;]"..
 	"list[current_name;dst;5.75,1.5;1,1;]"..
@@ -31,8 +33,10 @@ end
 local inactive_formspec = "size[9,8.75]"..
 	"background[-0.19,-0.25;9.41,9.49;crafting_inventory_furnace.png]"..
 	mcl_vars.inventory_header..
+	"label[0,4;"..minetest.formspec_escape(minetest.colorize("#313131", S("Inventory"))).."]"..
 	"list[current_player;main;0,4.5;9,3;9]"..
 	"list[current_player;main;0,7.74;9,1;]"..
+	"label[2.75,0;"..minetest.formspec_escape(minetest.colorize("#313131", S("Furnace"))).."]"..
 	"list[current_name;src;2.75,0.5;1,1;]"..
 	"list[current_name;fuel;2.75,2.5;1,1;]"..
 	"list[current_name;dst;5.75,1.5;1,1;]"..

mods/ITEMS/mcl_furnaces/locale/mcl_furnaces.de.tr

@@ -5,3 +5,4 @@ Use the furnace to open the furnace menu. Place a furnace fuel in the lower slot
 Use the recipe book to see what you can smelt, what you can use as fuel and how long it will burn.=Benutzen Sie das Rezeptbuch, um zu sehen, was Sie schmelzen können und was Sie als Brennstoff benutzen können und wie lange dieser brennt.
 Burning Furnace=Aktiver Ofen
 Recipe book=Fertigungsbuch
+Inventory=Inventar

mods/ITEMS/mcl_furnaces/locale/template.txt

@@ -5,3 +5,4 @@ Use the furnace to open the furnace menu. Place a furnace fuel in the lower slot
 Use the recipe book to see what you can smelt, what you can use as fuel and how long it will burn.=
 Burning Furnace=
 Recipe book=
+Inventory=