AP_NavEKF : Fix bug that leaves height unconstrained in static mode
AP_TECS : Add protection for airspeed runaway due to pitch errors
AP_NavEKF : Add low speed magnetometer calibration option
AP_NavEKF : Add sideslip constraint to allow plane flight without magnetometer
AP_NavEKF : update comments
AP_NavEKF : Make all compass use autodetect
AP_NavEKF : enable operation without a compass for planes