Dev/apc40 ashley

these changes hook up the APC40 to control the FlightGUI. with the exception of the sliders, if you change something via the FlightGUI, it should also update the state of the APC40.

I would like to be able to select a pattern for a channel by pushing a button on the drumpad, but I haven't been successful in figuring out how to do so. Any ideas @plevis? See 73fd087b for use case figured it out!

We still need to map the master controls to the knobs up top. The play/record functionality could be mapped too, but seems less important.