Unintended consequences.  I.e., it doesn't work on BeagleBone.
AP_GPS: zero state structure on driver release

this ensures no values are left from the previous driver
AP_GPS: handle multiple GPS in GPS setHIL()
DataFlash: hdop is unsigned
Replay: handle multiple GPS sensors
Plane: update for GPS.setHIL() API
Rover: update for gps.setHIL() API
Copter: update for gps.setHIL() API
update
Merge branch 'master' into local
UPdate