Flight Tasks: add new trajectory smoothing flight task & library

Derivation by Mathieu Bresciani:
https://github.com/Auterion/trajectory_generator

src/modules/mc_pos_control/mc_pos_control_main.cpp

@@ -917,6 +917,10 @@ MulticopterPositionControl::start_flight_task()
 			error =  _flight_tasks.switchTask(FlightTaskIndex::Sport);
 			break;
 
+		case 3:
+			error =  _flight_tasks.switchTask(FlightTaskIndex::ManualPositionSmoothVel);
+			break;
+
 		default:
 			error =  _flight_tasks.switchTask(FlightTaskIndex::ManualPosition);
 			break;

src/modules/mc_pos_control/mc_pos_control_params.c

@@ -633,12 +633,13 @@ PARAM_DEFINE_FLOAT(MPC_TKO_RAMP_T, 0.4f);
  * 	 and jerk limits.
  * 2 Sport mode that is the same Default position control but with velocity limits set to
  * 	 the maximum allowed speeds (MPC_XY_VEL_MAX)
+ * 3 Smooth position control with maximum acceleration and jerk limits (different algorithm
+ *   than 1).
  *
- * @min 0
- * @max 2
  * @value 0 Default position control
  * @value 1 Smooth position control
  * @value 2 Sport position control
+ * @value 3 Smooth position control (Velocity)
  * @group Multicopter Position Control
  */
 PARAM_DEFINE_INT32(MPC_POS_MODE, 1);