Scrub or replace MAVlink messages

[bsutherland333]

Our current communication protocol, MAVlink, has some redundant information that could be removed to minimize the amount of data we push across serial.

We've also talked about replacing MAVlink entirely with a custom streamlined packet system, since most of our MAVlink packets are custom packets anyways. This would have the advantage of a smaller, simpler code base that has smaller packets, increasing our possible serial bandwidth.