Rover: removed demo_servos()

doesn't do much good on rovers, and just slows boot
Plane: fixed setting of waypoint when not in AUTO

this fixes a bug where the next waypoint is set incorrectly if set via
MAVLink when not in AUTO
AP_AHRS: debounce the GPS/compass consistency test

we will only consider the compass inconsistent with GPS if it is off
for more than 2 seconds
AP_BattMonitor: added set_monitoring() API

needed for test sketch