Sub: Disable input hold on disarm

ArduSub/Sub.h

@@ -643,6 +643,7 @@ private:
     void handle_jsbutton_press(uint8_t button,bool shift=false,bool held=false);
     JSButton* get_button(uint8_t index);
     void default_js_buttons(void);
+    void clear_input_hold();
     void init_barometer(bool save);
     void read_barometer(void);
     void init_rangefinder(void);

ArduSub/joystick.cpp

@@ -550,3 +550,11 @@ void Sub::set_neutral_controls()
 
     hal.rcin->set_overrides(channels, 10);
 }
+
+void Sub::clear_input_hold()
+{
+    xTrim = 0;
+    yTrim = 0;
+    zTrim = 0;
+    input_hold_engaged = false;
+}

ArduSub/motors.cpp

@@ -120,6 +120,9 @@ void Sub::init_disarm_motors()
     // disable gps velocity based centrefugal force compensation
     ahrs.set_correct_centrifugal(false);
     hal.util->set_soft_armed(false);
+
+    // clear input holds
+    clear_input_hold();
 }
 
 // motors_output - send output to motors library which will adjust and send to ESCs and servos