Python-ly

Changed

- node and slexer are no longer toplevel modules; only the ly package

Changed

- Large MusicXML export improvements, contributed by Peter Bjuhr (MusicXML
export is still experimental)

Fixed

- Handle german pitch names asas and heses correctly when writing those
- Don't transpose chord argument of \stringTuning command
- Python 3 robustness improvements

Changed

- Small MusicXML export improvements, contributed by Peter Bjuhr (MusicXML
export is still very experimental)

Fixed

- Fix transposing when alterations would be more than a double sharp or double
flat; handle it by moving the note, just like LilyPond does it
- Python 3 installation fixes

Added

- New command 'highlight' ('hl') to create syntax-highlighted HTML files of
LilyPond source files (or any file that is understood by ly.lex)
- New, very experimental, command 'musicxml' to export music to MusicXML

Added

- New commands 'abs2rel' and 'rel2abs' that convert \relative music to
absolute and vice versa
- Support for Python 3. Not all of the ly python module has already been
tested, but installing and running the various ly commands works well.

Initial release.