MQTT: WIP, destroys paho client during failure handling at init and at cleanup. Use mutex to protect retrieve.
<?xml version='1.0' encoding='utf-8'?>
<SVGHMI xmlns:xsd="http://www.w3.org/2001/XMLSchema" OnWatchdog="echo Watchdog for {name} !" WatchdogInitial="10" WatchdogInterval="5" EnableWatchdog="true" Path="{name}"/>