Auto traj - generate heading from trajectory velocity vector if possible

src/lib/FlightTasks/tasks/AutoLineSmoothVel/FlightTaskAutoLineSmoothVel.hpp

@@ -69,9 +69,11 @@ protected:
 	void _setDefaultConstraints() override;
 
 	inline float constrain_one_side(float val, float constrain);
-	void _generateHeadingAlongTrack(); /**< Generates heading along track. */
+	void _generateHeading();
+	bool _generateHeadingAlongTraj(); /**< Generates heading along trajectory. */
 	void _updateTrajConstraints();
 	void _prepareSetpoints(); /**< Generate velocity target points for the trajectory generator. */
 	void _generateTrajectory();
 	VelocitySmoothing _trajectory[3]; ///< Trajectories in x, y and z directions
+	float _yaw_sp_prev;
 };