Refactor Arduino code

Should clean up/rewrite the code running on the D32s.

• encapsulate the different types of controls to their own functions (right now it's all written in long form)
• Adapt Trellis code to allow for momentary or latching control.
• read sensors based on a timer and sampling rate, instead of delay() call
• create MIDI ins to set functionality of each control (momentary/latch/continuous) and adjust sample rate