FlightTaskManualAltitude: yawspeed filter remove line with no effect, comments

FlightTaskManualAltitude: declaration order

Addressing @bkueng's review comments.

src/lib/flight_tasks/tasks/ManualAltitude/FlightTaskManualAltitude.cpp

@@ -328,7 +328,6 @@ void FlightTaskManualAltitude::_lockYaw()
 	// hold the current heading when no more rotation commanded
 	if (!PX4_ISFINITE(_yaw_setpoint)) {
 		_yaw_setpoint = _yaw;
-		_yawspeed_setpoint = NAN;
 	}
 }
 

src/lib/flight_tasks/tasks/ManualAltitude/FlightTaskManualAltitude.hpp

@@ -89,6 +89,13 @@ private:
 	bool _isYawInput();
 	void _unlockYaw();
 	void _lockYaw();
+
+	/**
+	 * Filter between stick input and yaw setpoint
+	 *
+	 * @param yawspeed_target yaw setpoint desired by the stick
+	 * @return filtered value from independent filter state
+	 */
 	float _applyYawspeedFilter(float yawspeed_target);
 
 	/**
@@ -118,6 +125,7 @@ private:
 
 	uORB::SubscriptionData<home_position_s> _sub_home_position{ORB_ID(home_position)};
 
+	float _yawspeed_filter_state{}; /**< state of low-pass filter in rad/s */
 	uint8_t _reset_counter = 0; /**< counter for estimator resets in z-direction */
 	float _max_speed_up = 10.0f;
 	float _min_speed_down = 1.0f;
@@ -131,6 +139,4 @@ private:
 	 * _dist_to_ground_lock.
 	 */
 	float _dist_to_ground_lock = NAN;
-
-	float _yawspeed_filter_state{};
 };