Finished changing lowest note to C5

Also improved performance of play/pause button and tempo slider.

TODO for Derek:
   Finish fixing load
   Finish optimizing generator
   Finish removing redundant set value calls
   Improve performance of first note selected when app starts and nothing is
      playing

TODO for you Max:
   Work with Darren on graphics (keep me posted)
   Drop sound files an octave: C4 - B5 is less hard on the ears
   Add another instrument + menu dropdown support
      I guess we're moving save/load back down on the main screen