improve serial hotplug (#389)

* - disable device when error indecates that the problem is not solvable on reconnect
- introduce a preOpenDelay of 2 seconds (currently value is hardcoded)

* rs232:
- make preOpenDelay available via webui
- fix preOpenDelay
- add basic usb serial detection

* - revert 3819ae7
- fix schema files

* make json checks compat with utf8+bom

* make shutdown effect a bit more flexible

libsrc/leddevice/LedDeviceAdalight.h

@@ -22,6 +22,9 @@ public:
 
 	virtual bool init(const QJsonObject &deviceConfig);
 
+public slots:
+	void receivedData(QByteArray data);
+
 private:
 	///
 	/// Writes the led color values to the led-device
@@ -32,6 +35,6 @@ private:
 	virtual int write(const std::vector<ColorRgb> & ledValues);
 	
 	const short _headerSize;
-	bool _ligthBerryAPA102Mode;
+	bool        _ligthBerryAPA102Mode;
 };