Eliminate USB packets from the ground station using constant overhead byte stuffing

Right now, we send a fixed length packet, and the ground station flushes the receive buffer after every successful packet reception. This means that multiple adjacent packets which arrived too quickly, will simply get discarded by the laptop side of the groundstation. I have a pull request open to do the same trick with CRC that we do for the ADC board, but an algorithm like constant overhead byte stuffing http://www.stuartcheshire.org/papers/cobsforton.pdf is actually designed to do this. Look into it and see if it makes sense to use