Method unsubscribeOutput

src/midiloopback.cpp:78–83

		return outputDevice;
	}
	void unsubscribeOutput(int deviceId, midi::Output* output) override {
		midi::OutputDevice* outputDevice = getDevice(deviceId);
		if (!outputDevice)
			return;
		outputDevice->unsubscribe(output);
	}

	// Custom methods
	Device* getDevice(int deviceId) {