Add Track levels & Track sampleLoopWindow changes to the event (undo/redo) stack
fix loopWindowSet events
Fix Track delete bug where track's notes weren't being destroyed properly before track deletion
Fix yOffset scrolling on MidiView
Fix ArrayIndexOutOfBounds error which could happen when a pointer touched below all tracks in MidiView after tracks had been deleted
Fix bug where setting a non-empty TextMesh to an empty string did not update the mesh
Add optional touchTransform to touchableViews to account for views which are being translated when rendered (so their actaul position doesn't match with apparent touch pointer positions)
prevent region select on MidiView if a note is being touched