Handling unicode paths

As far as I can see, it is not possible to use paths on Windows such as C:\Överkörd\Überförare\, maybe paths should be considered UTF-8, then convert to wchar_t* for use with std::ofstream/ifstream.

I don't think UTF-8 has anything to do with wchar_t, you can encode UTF-8 with char*. The usage of wchar_t is not recomended, specially if you want to maintain your code cross compilable (wchar_t may have different meaning for different platforms)