SVGHMI: Widget transform before DnD now should have HMI path as a parameter, but this path isn't computed for some reason... WIP.

SVGHMI: Widget DnD to Inkscape : Added source SVG widget label parsing and pass selecte HMI subtree to XSLT tranform, so that SVG containing multiple widgets can later be matched against hmi tree fragments, in order to DnD complex groups of widgets.

SVGHMI: Widget Library Picker now transforms SVG widget before allowing DnD. Transform is just identity forn now, but label parsing have already been included. To be continued.