Improved and updated docs were the main focuses of the new release, but you will also find:
- Many improvements and fixes to the harmony.Harmony object.
- Freezing/Thawing of Streams that were originally MIDI files now works.
- Better handling of repeat endings.
- Measure suffixes are handled more "musically"
- Easier setup on UNIX systems and using PIP and other tools.
- Improvements in Lilypond output
- Documentation on using music21 with iPython in a multi-core, cluster environment.
This version of music21 is a larger download than before (68MB as opposed to 30MB) because all of the documentation in both old and new formats is included. The next version will return to normal size.
One backwards incompatible change: Stream.elements now returns a tuple instead of a List. This is done to emphasize that .elements should not be changed. Instead use Stream.append, .remove, .insert, or subscript the Stream object. Chord.pitches also returns a tuple instead of a List as well.
Thanks to everyone for their contributions and comments that make music21 work well!