Sparky BGC

This creates a second target for a Sparky board with the brushless
gimbal controller daughter board attached as well as the pios driver
to control it.

The gimbal has been fairly well tested:
https://vimeo.com/70779978
https://vimeo.com/66987484

And can track communicate via CAN to track coordinates
https://vimeo.com/67528638

P.S. ignore the library.mk related changes as those will disappear once #835 merges