Grace note problems

[AaronDavidNewman]

Grace notes are really hard to work with.

There is no UI way to select grace notes
grace note selections are not preserved when tracker map is updated
grace notes don't honor accidentals and courtesy accidentals in the same way as normal notes

[AaronDavidNewman]

This is fixed to some extent - it is possible to navigate between grace notes and 'real' notes now, and to edit/remove them. A few bugs remain:

• cannot create 1/4 note grace notes, causes exception
• enharmonics don't work, end up affected the note
• no playback