integrate optional NPFG library for wind-aware fixed-wing guidance

msg/CMakeLists.txt

@@ -112,6 +112,7 @@ set(msg_files
 	mission_result.msg
 	mount_orientation.msg
 	navigator_mission_item.msg
+  npfg_status.msg
 	obstacle_distance.msg
 	offboard_control_mode.msg
 	onboard_computer_status.msg

msg/npfg_status.msg

@@ -0,0 +1,16 @@
+uint64 timestamp                # time since system start (microseconds)
+
+uint8 wind_est_valid            # (boolean) true = wind estimate is valid and/or being used by controller (also indicates if wind est usage is disabled despite being valid)
+float32 lat_accel               # resultant lateral acceleration reference [m/s^2]
+float32 lat_accel_ff            # lateral acceleration demand only for maintaining curvature [m/s^2]
+float32 bearing_feas            # bearing feasibility [0,1]
+float32 bearing_feas_on_track   # on-track bearing feasibility [0,1]
+float32 signed_track_error      # signed track error [m]
+float32 track_error_bound       # track error bound [m]
+float32 airspeed_ref            # (true) airspeed reference [m/s]
+float32 bearing                 # bearing angle [rad]
+float32 heading_ref             # heading angle reference [rad]
+float32 min_ground_speed_ref    # minimum forward ground speed reference [m/s]
+float32 adapted_period          # adapted period (if auto-tuning enabled) [s]
+float32 p_gain                  # controller proportional gain [rad/s]
+float32 time_const              # controller time constant [s]