Replay Menu: Support non-ASCI characters

[elexis]

Some users, f.e. with czech characters in the replay path run into that case:

Couldn't open %s. Non-latin characters are not supported yet

Thus the replay menu is entirely empty to affected users.

It occurs in VisualReplay::LoadReplayData:

	const CStr fileName = replayFile.string8();
	std::ifstream* replayStream = new std::ifstream(fileName.c_str());

Previously utf8_from_wstring(fileName.string()) and OsString(filePath).c_str() have been used, see r17314 r17356. It might be a bug in any of the string conversion functions, or even FileExists

Any proposed solution should be tested with all operating systems.

Reported by Bouddica.