Adds functionality to MIDISequence/MIDIChannel.

Adds several methods to MIDISequence/MIDIChannel,
though some of these may be removed before the
1.0 release. Also, MIDIChannels now have access
to their entire backing MIDIFile, because
they need to add meta information to track 0.
Adds `addEvents()` method to MIDITrack
Whitespace changes
add more emacs-specific files to gitignore
Ignore dist/ until refactor complete
Update tasklist