LP-598 Autotakeoff Corrections

LP-598 Fix auto-takeoff velocity

Velocity setpoint with the wrong sign, causing the uav to remain on the ground during the first autotakeoff.

LP-598 clean-ups

• AltitudeAtState is corrected to be a positive altitude above ground.

• remove unneeded call to StabilizationDesiredGet()

• update timeout values in descriptions so they match the code

LP-598 Followed Laurent's suggestions that makes it possible to remove duplicated code

• update assessAltitude() to return the altitude. Code that duplicated the calculation has been removed.

• make pretty & update headers