SITL: Add compassmot interference
Replay: fixed for changes to AP_Compass HIL API
AP_InertialSensor: added VibTest sketch

logs all accel data at high rate to SD card
AP_AHRS: added healthy() function

this will be used to report when the AHRS subsystem becomes unhealthy
GCS_MAVLink: merge in latest upstream XML changes
GCS_MAVLink: regenerated MAVLink headers
AP_NavEKF: Improved divergence detection and reset

Divergence is now detected by looking for very large changes in the gyro
bias. This will cause the filter to be reset and declared unhealthy for
10 seconds.

Don't reset filterDiverged status immediately during reset

Set filterDiverged true if covariance blows up

Add fault status reporting
DataFlash: Add EKF fault status logging
Replay: Add EKF fault status logging message to EKF4
GCS_MAVLink: added MAV_SYS_STATUS_AHRS

will be used to indicate AHRS health
GCS_MAVLink: re-generate with addition of MAV_SYS_STATUS_AHRS
Rover: added reporting of AHRS health
Copter: added reporting of AHRS health
Plane: added reporting of AHRS health
AP_NavEKF: fixed up handling of bitfields in faultStatus

Pair-Programmed-With: Paul Riseborough <p_riseborough@live.com.au>
AP_AHRS: fixed check of accel sensor health

we need to check health of each accelerometer separately
AP_AHRS: when no accel info available in buffer use current value

this prevents an initialisation error, and is reasonable in flight too

Pair-Programmed-With: Paul Riseborough <p_riseborough@live.com.au>