Co-authored-by: Andrew Tridgell <andrew@tridgell.net>
uses the elements out of the simulated GPS data "d", rather than going to the parameters in teh simulated GPS "backends".
* Rename NMEA heading to ground_course_deg
* Rename heading() utility to ground course (it was wrong)
* Add _rad prefix to be pedantic about units
* Add missing degrees conversion in NMEA because NMEA is not SI
Signed-off-by: Ryan Friedman <ryanfriedman5410+github@gmail.com>