trebleStaff, bassStaff, and mouseStuckTo (!!!!)

-replaced gs.staff with trebleStaff/bassStaff
-mouseMoveHandler sets mouseStuckTo
-addNote/mouseDownHandler/etc callse mouseStuckTo
-notesAdded counter accounts for entire GS (both treble and bass)
-ledger lines draw and clear based on mouseStuckTo

awesomeness is awesome