AUDIO: Split event processing from MidiParser::onTimer

This is to prepare for overriding more of this functionality in SCI.
AUDIO: Let jumpToTick use processEvent too
AUDIO: Simplify MidiTracker::processEvent return value
SCI: Move MIDI event processing out of parseNextEvent
AUDIO: Simplify SCI inFastForward flag by moving it to MidiParser
SCI: Handle !fireEvents in processEvent
Merge branch 'master' into sci_midiparser

Conflicts:
	engines/sci/sound/midiparser_sci.cpp
Merge pull request #398 from wjp/sci_midiparser

SCI: Move MIDI event processing out of parseNextEvent