PCjr support.
Rewrote the generator, so I can reuse more code between PCjr and speaker output.
Added function to set master volume and to switch between PCjr and speaker.
svn-id: r8185
and script interpreter for GF_OLD_BUNDLE music resources.
We'll try to get the waveform generator into a
MidiDriver wrapper for use with the 'SPK' resources
of later games, but this is usable for now.
Great work, Hoenicke!
svn-id: r8023
