captouch edge detection and background playback

We assume that recording is supposed to happen on the edges of presses since otherwise it is very hard to input a sequence without a lot of repeats.

This is absolutely not your fault, the API is confusing, see the note here: https://docs.flow3r.garden/app/api/input.html#inputcontroller

Also we added the feature to continue playing in the background as a drum computer (with limited accuracy for now as we're using micropython callbacks).

Other things:

• updated bl00mbox use to new API
• added a get_help() method for the onboard help viewer
• reset LEDs when petals are released

This bumps the version to 14.