Implement MAV_CMD_DO_CHANGE_SPEED throttle

src/modules/navigator/navigator_main.cpp

@@ -159,6 +159,7 @@ Navigator::Navigator() :
 	_param_rcloss_act(this, "RCL_ACT"),
 	_param_cruising_speed_hover(this, "MPC_XY_CRUISE", false),
 	_param_cruising_speed_plane(this, "FW_AIRSPD_TRIM", false),
+	_param_cruising_throttle_plane(this, "FW_THR_CRUISE", false),
 	_mission_cruising_speed(-1.0f)
 {
 	/* Create a list of our possible navigation types */
@@ -725,6 +726,17 @@ Navigator::get_cruising_speed()
 	}
 }
 
+float
+Navigator::get_cruising_throttle()
+{
+	/* Return the mission-requested cruise speed, or -1 */
+	if (_mission_throttle > 0.0f) {
+		return _mission_throttle;
+	} else {
+		return _param_cruising_throttle_plane.get();
+	}
+}
+
 float
 Navigator::get_acceptance_radius(float mission_item_radius)
 {