Make Ogg music track names configurable

Hi,
I played around with Shadow Warrior and JFSW today and noted some things that could be improved (or in one case fixed). As your code (at least the parts I touched) was fun to work with, I fixed those things myself; see also jonof/jfaudiolib#1 and jonof/jfbuild#4 :-)

This pull request makes the Ogg music track names configurable via sw.cfg, (with "OggTrackName"), so you can for example set it to "MUSIC/Track??.ogg" for the SW Steam version.
"??" is used as a placeholder for the actual track number, apart from that any path up to a length of 255 chars (relative to the base SW directory) can be configured.
It defaults to "track??.ogg", like before.

Cheers,
- Daniel