Grid-instrument

I've just added the all-important play.py file that lets you actually use this code in a somewhat plug-and-play fashion.

- Fixed a bug that was preventing the PyPI package from working correctly.

- Moved the settings button to be the top button on the right-hand side (same as Launchpad95 scripts)
- Added a new, chromatic layout. To switch to chromatic, hold the settings button (top button on right side) and tap the 7th button on the top row. To switch back to "Diatonic 4th", hold the settings button and tap the 6th button.