After considering the different options, I concluded that it is important to
support the Qt way of doing things.
If the App programmer wants to do things the Qt way, it should be possible.
Cleaned up the responsibilities between Editor, model and View
Now model exposes translation between QModelIndex and PdmUiItem
Selection inteface implementation is handled by editor, and forwarded to View
Also started renaming of SlectionManager update enabeling
