list of music types supported. This was done because now
PC speaker support must be treated separately, along with
Adlib and native (GM/MT32) support.
This fixes a problem with games that don't support PC speaker
(including V5 games that don't parse SPK resources yet)
being run with -epcspk or -epcjr. Those games now properly
switch to -enull so that music resources still get parsed
and music/script synchronization mechanisms don't break.
svn-id: r9703