refs #641, improvements/fixes of orderable lists / models / views

* set sort order automatically to IndexOrder when changing order of items
* call onChanged when model is changed and then update view (needed when model is changed directly, not via view)
* support for digest signal so redundant updates can be avoided
* renamed rowCountChanged (signal) to modelDataChanged - detecting row count changes only was useless
* updated Doxygen / fixed typos

src/blackgui/models/listmodeldbobjects.h

@@ -73,6 +73,9 @@ namespace BlackGui
             virtual void moveItems(const ContainerType &items, int position) override;
             //! @}
 
+            //! Sort order to order property BlackMisc::IOrderable::IndexOrder
+            void setSortColumnToOrder();
+
         protected:
             //! Constructor
             COrderableListModelDbObjects(const QString &translationContext, QObject *parent = nullptr);