Move docstring for Changelist.changes() to the right place
ly/tokenize.py: track token changes by (line, column) tuple

This will allow us to use ly.tools.relativeToAbsolute() and
then map (line, column) tuples to absolute pitches
remove overly scoped try/except block

It was obscuring valuable debug.
only show output of midi-rubato in debug mode
convert to absolute pitches
compare absolute pitches rather than within the octave (issue #20)

https://github.com/aspiers/ly2video/issues/20
add debugging to MIDI file reading code
added debug to getFilteredIndices() and mergeNearbyIndices()
fix ordering in docstrings
improve docstrings describing notesAndTies
add support for microtones by recognising MIDI pitch bends (issue #18)

https://github.com/aspiers/ly2video/issues/18
fix bug with handling of tokens like "~[" and "~]"
debug tempo changes
output MIDI resolution
fix frame estimation
fix bug when there's only one tempo