Fix stock burn termination and bring back MANEUVER_COT

Still don't know if MANEUVER_COT works, but it is back.

The expression:

Quaternion.FromToRotation(VesselState.forward, VesselState.thrustForward) * VesselState.forward

Looks a little useless but FromToRotation returns identity when
thrustForward is [0,0,0] which fixes things for the non-thrust case.

More importantly this fixes stock-style burn termination to work
correctly again and it measure the angle to the actual maneuver node
rather than the angle to the frozen inertial direction (which really
shouldn't have worked at all, dunno why it eventually did stop).

Signed-off-by: Lamont Granquist <lamont@scriptkiddie.org>

MechJeb2/MechJebModuleNodeExecutor.cs

@@ -109,7 +109,7 @@ private enum Mode { ONE_NODE, ONE_PNODE, ALL_NODES }
         private Mode _mode = Mode.ONE_NODE;
 
         public  bool     BurnTriggered;
-        private double   _dvLeft; // for Principia
+        private double   _dvLeft;    // for Principia
         private Vector3d _direction; // de-rotated world vector
 
         public override void Drive(FlightCtrlState s) => HandleUllage(s);
@@ -152,7 +152,7 @@ public override void OnFixedUpdate()
                     return;
                 }
 
-                Core.Attitude.attitudeTo(Planetarium.fetch.rotation * _direction, AttitudeReference.INERTIAL, this);
+                Core.Attitude.attitudeTo(Planetarium.fetch.rotation * _direction, AttitudeReference.INERTIAL_COT, this);
 
                 double ignitionUT = CalculateIgnitionUT(node);
 
@@ -172,10 +172,10 @@ public override void OnFixedUpdate()
             {
                 //check if we've finished a node:
                 ManeuverNode node = Vessel.patchedConicSolver.maneuverNodes[0];
-                _dvLeft = node.GetBurnVector(Orbit).magnitude;
+                _dvLeft    = node.GetBurnVector(Orbit).magnitude;
                 _direction = NextDirection();
 
-                if (BurnTriggered && AngleFromTarget() >= 0.5 * PI)
+                if (BurnTriggered && AngleFromNode() >= 0.5 * PI)
                 {
                     BurnTriggered = false;
 
@@ -199,7 +199,7 @@ public override void OnFixedUpdate()
                     }
                 }
 
-                Core.Attitude.attitudeTo(Planetarium.fetch.rotation * _direction, AttitudeReference.INERTIAL, this);
+                Core.Attitude.attitudeTo(Planetarium.fetch.rotation * _direction, AttitudeReference.INERTIAL_COT, this);
 
                 double ignitionUT = CalculateIgnitionUT(node);
 
@@ -217,9 +217,16 @@ public override void OnFixedUpdate()
             }
         }
 
-        private double AngleFromTarget()
+        private double AngleFromNode()
         {
-            Vector3d fwd = VesselState.forward.normalized;
+            Vector3d fwd = Quaternion.FromToRotation(VesselState.forward, VesselState.thrustForward) * VesselState.forward;
+            Vector3d dir = Vessel.patchedConicSolver.maneuverNodes[0].GetBurnVector(Orbit).normalized;
+            return SafeAcos(Vector3d.Dot(fwd, dir));
+        }
+
+        private double AngleFromDirection()
+        {
+            Vector3d fwd = Quaternion.FromToRotation(VesselState.forward, VesselState.thrustForward) * VesselState.forward;
             Vector3d dir = (Planetarium.fetch.rotation * _direction).normalized;
             return SafeAcos(Vector3d.Dot(fwd, dir));
         }
@@ -273,8 +280,8 @@ private void HandleAutowarp(double ignitionUT)
             }
 
             if (MuUtils.PhysicsRunning()
-                    ? AngleFromTarget() < Deg2Rad(1) && Core.vessel.angularVelocity.magnitude < 0.001
-                    : AngleFromTarget() < Deg2Rad(2))
+                    ? AngleFromDirection() < Deg2Rad(1) && Core.vessel.angularVelocity.magnitude < 0.001
+                    : AngleFromDirection() < Deg2Rad(2))
                 Core.Warp.WarpToUT(ignitionUT - 3);
             else
                 Core.Warp.MinimumWarp();