Add MTG-style formspec background

mods/tutorial_default/README.txt

@@ -106,6 +106,8 @@ Zeg9 (CC BY-SA 3.0):
 paramat (CC BY-SA 3.0):
   wieldhand.png, based on character.png by Jordach (CC BY-SA 3.0)
   default_grass_*.png
+  gui_hotbar.png
+  gui_hotbar_selected.png
 
 brunob.santos (CC BY-SA 4.0):
   default_desert_cobble.png
@@ -127,7 +129,10 @@ BlockMen (CC BY-SA 3.0):
   default_book.png
   default_paper.png
   default_stick.png
-  gui_*.png
+  gui_formbg.png
+  gui_furnace_arrow_bg.png
+  gui_furnace_arrow_fg.png
+  gui_hb_bg.png
 
 Glass breaking sounds (CC BY 3.0):
   1: http://www.freesound.org/people/cmusounddesign/sounds/71947/

mods/tutorial_default/player.lua

@@ -148,6 +148,20 @@ minetest.register_on_joinplayer(function(player)
 	if not minetest.settings:get_bool("creative_mode") then
 		player:set_inventory_formspec(default.gui_suvival_form)
 	end
+
+	-- Minetest Game-style formspec prepend
+	local formspec = [=[
+		listcolors[#00000069;#5A5A5A;#141318;#30434C;#FFF]]=]
+	local name = player:get_player_name()
+	local info = minetest.get_player_information(name)
+	if info.formspec_version > 1 then
+		formspec = formspec .. "background9[5,5;1,1;gui_formbg.png;true;10]"
+	else
+		formspec = formspec .. "background[5,5;1,1;gui_formbg.png;true]"
+	end
+	player:set_formspec_prepend(formspec)
+
+	-- Hotbar
 	player:hud_set_hotbar_image("gui_hotbar.png")
 	player:hud_set_hotbar_selected_image("gui_hotbar_selected.png")
 end)