corrected some wrong units (used in airspeed calculation)
more fixes for the airspeed readout
airspeed (pitot) offset calibration
Hotfix: Removed spurious break
fixed a typo
commander app sets an airspeed_valid flag in the vehicle status
small cleanup
small printf change
Merge branch 'master' of github.com:PX4/Firmware into px4io-i2c
Merge pull request #206 from thomasgubler/airspeed

airspeed calculation
Merged master