add to do file
fix DAC output setting
add support for interrupts and input bit flipping
working prototype of digital side of sequencer

runs fixed output sequence continually
rework event queue a little

events now contain 3 x uint8 values (enough for our MIDI needs)
simple MIDI receiver implementation

handles a small, receive-only MIDI subseq. Plumbs received MIDI
messages into the event queue.
breadboard prototype configuration/test harness

MIDI->CV and CV sequencer