Add baud rate command line option to console.
Group message IDs and add structs that define the message payloads.
Make messages with zero high nibble unmaskable. Update UART settings for XBee.
Big update adds preliminary support for differential solutions.

Several updates to the console and message payload formats. So much for atomic commits...
CRC functions moved to libswiftnav.
Add init button to the baseline view.
Filter baselines >200m for now
Add hacky baseline logging.
Temporarily limit to 9 tracking channels.