Fix the localisation code about frontend HOT 4 OPEN

If #461 update looks like it solved it, this issue could be closed.

from frontend.

I'm not sure it did - I'm honestly getting confused but I think this is actually a frontend issue (the whole special characters in filenames not working problem.

from frontend.

I've been looking at this again. I need to do some more research, but it appears Windows needs UTF-16 paths when handling anything non-ASCII. The converters would need to coordinate with the frontend on exactly how we want to format configuration files. Maybe include some metadata about paths? I'm not sure. I have a test program I've been working on that I need to complete so I have a good grasp of how it all works.

from frontend.

Not a frontend issue at all. For posterity:

Frontend correctly saves information in UTF8 configuration.txt, but the converters need to read those UTF8 strings, pipe the strings through std::filesystem::u8path() and then open directories and files for reading and writing using resulting std::filesystem::paths.

Current mechanism of passing SaveGame to the converter through *argv doesn't work as accepting UTF8 (technically wstring, so utf-16) filenames requires wmain() *wargv and is rather incompatible with anything non-windows. Savegame must go through configuration.txt same as other paths.

from frontend.