Each flag was previously a whole byte, now all of the flags only take up
4 bytes as they are represented by bit masks.
This is cleaner because the different kind of flags are now separated.
Additionally this changes the behaviour of arming slightly. When using
a switch to arm the aircraft will not arm unless the switch has been in
the off state once. This prevents arming if you power the aircraft with
a low throttle and the switch in the on position.
gps.c now only has code that deals with gps hardware, state and
messaging.
navigation.c now only has code dealing with flight
navigation/waypoints/home/hold/etc
