Currently const char * points into some random buffer with unclear
lifetime.
Instead use Common::String which ensures lifetime as long as a reference is
held.
This also removes the need of copying into existing buffers in HoF and MR.
UnkBuf* are gone as well.
Co-authored-by: athrxx <athrxx@scummvm.org>
Reorganize all files in sub directories. The file placement isn't as intuitive as it might be for other engines, which is probably the reason why this hasn't been done before.