Make "5 Grooves" practice-able in app

[nathanleiby]

• [x] Choose 5 grooves to learn - these ones
• [ ] Transcribe them manually
  • [x] (funk) Cup Stacker - verse
  • [ ] (prog rock) "Atlus Novus" - Scale the Summit - starting 51s
  • [ ] Samba
  • [ ] Green Day - "Basket Case" - verse (existing tab m35 - m51)
  • [ ] Nightrider
• [ ] Determine what features need to be added + Implement those features
  • [ ] variable loop duration #17
  • [ ] 6/8 meter
• [ ] Add the groove to the app