calculate total airflow over elevons using physical of flow behind propeller. read local position topic for future use.

dynamic estimation of baro_gps_offset

Update EKF estimator to most recent version from Paul Riseborough

Record devid to SENS_MAG_ID during mag calibration
Verify devid matches SENS_MAG_ID during preflight_check

README: Add link to contribution.md

Commander home pos cleanup

Commander: Fix for resetting home timestamp on arm

Commander: Play tune on disarm and when safety switch is toggled