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).