Added Thrust Torque readout to Editor and Flight

Shows the torque experienced by the ship at full throttle due to asymmetries in its build.
An other readout shows a pseudo-angle that approximates the directional error of the engine's thrust vectors (more human-readable than the kNm Torque number).
Reaction wheel torque is now kNm instead of kN
Simulation.cs: removed unused property ShipStartMass
Merge pull request #9 from mic-e/thrustdirectionerror

thrust torque + angle readout