Several adjustments to UI as discussed with Håkon and Alireza.
* add link/unlink command to right-click menu of axis
* select curve in project tree when clicking on legend item
* make sure internal legend is always visible when toggling plot
* fix issue when using sub plot as data source for axis range
Add support for a field to be linked to a value updated by code outside the object itself. Mark the linked field by using a background color and icons for linked/unlinked state.
The auto value states is set as attributes in the project xml file.
Add reference implementation in cafTestApplication, see Fwk/AppFwk/cafTests/cafTestApplication/MainWindow.cpp
* Tree View Editor: Avoid sending notification if selection is unchanged
* Use std++17 in test solution
* Move icons to icon factory
* add support for creating QIcon from SVG text string
