Some bugs corrected

Changes include:
- In file midi.h corrected a typo (gave a warning)
- In file sequencer.h added an attribute to the class MIDISequencerState
(see below)
- In file jdksmidi_sequencer.cpp corrected the GoTo... functions (they
stopped AFTER the proper event) and the MIDISequencerState::Process()
(if the sequencer was started on a beat it didn't send the first beat
marker message: it was necessary to add a new attribute to
MIDISequencerState class)
- In file jdksmidi_advancedsequencer.cpp corrected the functions
GoToZero(), SetMltChanged() and ExtractWarpPositions()