Copter: use Log_Write_Baro()

this gives the raw pressure and temperature, which is useful for
analysis, plus allows for more accurate log replay
AP_NavEKF : Improvements to staticMode robustness
AP_NavEKF : useAirspeed set automatically
AP_NavEKF : covariance prediction cleanup
AP_NavEKF: fixed detection of airspeed sensor

the get_airspeed() AHRS call can change as the user enables/disables
the airspeed sensor, plus it only gets enabled after the NavEKF
constructor runs.
AP_Math: added more operators to VectorN
AP_AHRS: added get_correct_centrifugal()

used by NavEKF to force static mode
AP_NavEKF: use AHRS get_correct_centrifugal()
AP_InertialSensor: fixed HIL for 400Hz INS
AP_AHRS: added get_armed() and set_armed() calls

will be used by NavEKF to determine static mode
AP_NavEKF: use ahrs->get_armed() for static mode demanded
Plane: use ahrs.get_armed()
Copter: set the ahrs.set_armed() flag
Rover: set the ahrs.set_armed() flag