SVGHMI: Add support for forcing widget update frequency with period longer than a second. As an example, "HMI:Display|10s@/myvar" updates variable every 10 seconds.
<?xml version='1.0' encoding='utf-8'?>
<SVGHMI xmlns:xsd="http://www.w3.org/2001/XMLSchema" OnWatchdog="echo Watchdog for {name} !" OnStart="xdg-open http://127.0.0.1:{port}/{name}" OnStop="echo Closing {name}" WatchdogInitial="10" WatchdogInterval="5"/>