Add menu for selecting the level font

By default, when you open the level editor to start a new level, the
level font will now match your VVVVVV language; so if you're, say,
Japanese, then you can make Japanese levels from the get-go. If you
want to make levels for a different target audience, you can change the
font via a new menu (map settings > change description > change font).
The game will remember this choice and it will become the new initial
level font.

desktop_version/src/Localization.cpp

@@ -15,6 +15,7 @@ namespace loc
 bool lang_set = false;
 std::string lang = "en";
 std::string lang_custom = "";
+std::string new_level_font = "";
 LangMeta langmeta;
 
 // language screen list