Added angleSAS parameter to SteeringHelper for Tweaking via kOS.

angleSAS can be added via a fourth parameter of setparam.
setparam (90,0,0,1.5) sets the angleSAS parameter to 1.5.
angleSAS determines the maximum angle between the vessel Rotation and
the vesselSAS.lockedHeading.
Sensible values range from 0.1 to 5, lower values for slower rotation
succession rates, higher values for quicker rotation succession rates.