MQTT: Implements reconnecting in publish thread in case thread is waken-up but client is disconnected.
Note: paho's lostConnection callback got already disabled in previous commit.
Widget syntax
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.. highlight:: text
HMI elements are SVG elements whose labels start with ``HMI:``::
HMI:WidgetType[|freq][[:param]...][[@a=path[,min][,max]]...][#expression]
Widget Type
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Update Frequency
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Parameters
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Variable bindings
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Enable expression
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