Add new parameter support for vector layer (WIP)
Add new parameter support in vectorl layer settings (WIP)
Init proprerties for layer vector
Add a dropdown list for the add layer button to let the user choose the layer type between: vector, raster, chart, WMS, Feature, Tileindex
Layer model - renaming
Layers - using layerModel instead of QStringListModel

This is far from perfect, but I could not encounter issues (segfaults)
at runtime, supposing that it does the work for now.