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
Re-using elements with Inkscape clones (svg:use)=================================================Re-use of pages---------------Re-use of widgets-----------------Re-use of SVG elements in widgets---------------------------------