The animation that plays when you fall through the sewage chute near the start
of the game had some issues. Fades were missing at several points, the middle
part of the animation was played only once and too slow, and when skipping the
animation it would only skip the currently playing part instead of the entire
animation.
To fix these issues, I've added an option to AnimationSequence to loop the
animation a number of times.
Distinction between music and SFX was made based on the most significant bit in
the sound number byte. This does not accurately reflect which MIDI sequences
are music or a sound effect.
Instead, I've added a flag which can be passed to
SoundManager::musicInterface_Play to indicate whether the sound is music or a
sound effect. All music is started from hard-coded animation sequences, so this
flag can be passed from ScummVM code when appropriate.
