NoteHead refactoring
- Heads now created on construction
- Refactoring of StaveNote
Refactored StaveNote.draw()
- Extracted separate draw() methods for each part of the StaveNote (drawModifiers(), drawFlag(), etc)
Cleanup
Continuing NoteHead refactor
- NoteHead now inherits from note, can be used stand-alone in a voice
- Factor out key styles into NoteHead
- Add notehead_tests.js
- Adding comments
Fixed lint issues. Disabled notehead tests.