Reactivate and enhance localization support

[winterheart]

Initially Descent 3 project supports 5 languages EFIGS (English, French, Italian, German, Spanish).

Current state of code with GOG / Steam resources allows select only English. Due font format limitations we can only support Latin-1 + additional symbols for European languages (ISO-8895-1?).

In order to enable wide localization support we need add Unicode support to grtext / grfont submodule, probably we need to implement new format of bitmap fonts with ability to define any glyph from Basic Multilingual Plane (up to 0x10000 symbols for all possible languages).

[Lgt2x]

Seconding this. Once this is done, I'd suggest we add a -lang [EN/FR/IT/GE/ES] runtime flag for language selection, and a settings menu. From what I could tell the last time I looked into it, you can only set used language by changing the config file.

[0xFADDAD]

There was also a Japanese language release by Imagineer Co., Ltd.
https://www.mobygames.com/game/1051/descent3/releases/
Not sure how far you would go to support it, but just wanted to put it out there.