beremiz

Extend HMI:JsonTable, create Edit CSV POU, create example, add some doc (#41)

* Extend Jsontable widget, create Edit CSV POU, create example for both

* Add doc for HMI:Image and HMI:JsonTable

* Expand example to include HMI:Image
PLC variables and local variables
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PLC variables start with ``/``
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Local Page variables start with ``.``
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Local HMI variables
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