Change from JSBSim:

Changed steering to use the rudder command rather than the rudder
position.  During taxi, the rudder trim shouldn't affect the steering
in any serious way.

This should be configurable in the aircraft file, since not all
aircraft use the rudder pedals for ground steering.

[In FlightGear, this may make it easier to taxi straight.]

src/FDM/JSBSim/FGLGear.cpp

@@ -308,7 +308,7 @@ FGColumnVector3& FGLGear::Force(void)
 
       switch (eSteerType) {
       case stSteer:
-        SteerAngle = SteerGain*FCS->GetDrPos();
+        SteerAngle = SteerGain*FCS->GetDrCmd();
         break;
       case stFixed:
         SteerAngle = 0.0;