No option to set BODY TO GPS

[OpenUAS]

With the event of more acurate UA position options like Piksi and also using Vicon and optitrac systems there is no setting for the airframe to set what we consider the Mid point of the aircraft a body_to_gps fot xyz or something could be introduced.

As example on my 4m plane there would be a 2 meter difference between DGPS sensor and midwheel landing gear.

Update:
Partially done with #1080, still TODO:

• also consider this offset when (re)setting local origin
• consider this offset/lever for velocity updates (when angular rates != zero)

Want to back this issue? Post a bounty on it! We accept bounties via Bountysource.