Walk Movement Controller Rotation Dependency Fix

Makes the movement velocity independent of the controller rotation.

Closes #658

Source/RWTHVRToolkit/Private/Pawn/Navigation/CollisionHandlingMovement.cpp

@@ -41,8 +41,11 @@ void UCollisionHandlingMovement::TickComponent(float DeltaTime, enum ELevelTick
 	{
 		// you are only allowed to move horizontally in NAV_WALK
 		// everything else will be handled by stepping-up/gravity
-		// so remove Z component for the input vector of the UFloatingPawnMovement
-		InputVector.Z = 0.0f;
+		// so rotate the input vector onto horizontal plane
+		const FRotator InputRot = FRotator(InputVector.Rotation());
+		const FRotator InputYaw = FRotator(0, InputRot.Yaw, 0);
+		InputVector = InputRot.UnrotateVector(InputVector);
+		InputVector = InputYaw.RotateVector(InputVector);
 		ConsumeInputVector();
 		AddInputVector(InputVector);
 	}