landdetector: add additional landdetection state

src/modules/land_detector/MulticopterLandDetector.h

@@ -74,6 +74,8 @@ protected:
 
 	virtual bool _get_ground_contact_state() override;
 
+	virtual bool _get_maybe_landed_state() override;
+
 	virtual bool _get_freefall_state() override;
 
 	virtual float _get_max_altitude() override;
@@ -139,6 +141,7 @@ private:
 	bool _has_position_lock();
 	bool _has_manual_control_present();
 	bool _has_minimal_thrust();
+	bool _has_low_thrust();
 };