Sub: add method to get throttle channel control_in, while applying

deadzone to center like angle type channels

ArduSub/Attitude.cpp

@@ -128,6 +128,11 @@ void Sub::set_throttle_takeoff()
     pos_control.init_takeoff();
 }
 
+int16_t Sub::get_throttle_control_dz()
+{
+	return (channel_throttle->pwm_to_angle() + 1000)/2;
+}
+
 // get_pilot_desired_throttle - transform pilot's throttle input to make cruise throttle mid stick
 // used only for manual throttle modes
 // returns throttle output 0 to 1000

ArduSub/Sub.h

@@ -1056,6 +1056,7 @@ private:
     void auto_terrain_recover_run(void);
 
     void translate_wpnav_rp(float &lateral_out, float &forward_out);
+    int16_t get_throttle_control_dz();
 
     bool surface_init(bool ignore_flags);
     void surface_run();