Copter: don't stop logging on disarm when LOG_WHEN_DISARMED is set
Copter: rework control switch debouncing
AP_Notify: Rework ToneAlarm_PX4 to play tones from local array
Copter: play various tones
Copter: allow radio failsafe while disarmed so that user can be notified
AP_NavEKF: Add attHealthy function
AP_AHRS_NavEKF: Don't fall back to DCM unless attitude states are NAN
AP_AHRS_NavEKF: overload get_accel_ef
DataFlash: Add UBX3 message for GPS accuracy figures
AP_GPS_UBLOX: Log GPS accuracy metrics