Externalize localizations

[Asdow]

Currently we have to compile and build several different localized .exe files due to hard coded text strings. All texts should be externalized to provide a possibility to change used language at runtime.

[CptMoore]

Considerations:

• Chinese has some special handling, that would need to be fixed first
• gamedir-languages currently works by overwriting the base (english) game, we would want to keep languages assets (xml, sti, etc..) side by side. That should be simple to do, since the vfs already supports overloading dirs during runtime
• cmake and github builds are easy to fix

[kitty624]

not sure if that's important, but there is this setting choice in ja2.ini
``
;******************************************************************************************************************************
; Only set this to 1, if you are running the Chinese version of the game.
;******************************************************************************************************************************

USE_WINFONTS = 0
``

and in this pr #151 for scaling tooltips, an issue with chinese using wfont was solved