Plane: mark a 2.73beta release
Plane: move baro init earlier in startup

this ensures it is initialised when CLI takeover by MP happens

Thanks to Prof Avi Levi for reporting this bug
autotest: display flight tracks on autotest web page
autotest: keep images in history
AHRS: add correct_centrifugal and flags structure
Copter: disable centrifugal correction when disarmed
Plane : Corrected typographical error in APM_Control/TuningGuide.txt