Order for addons added.
Root categories ordered as well.
Comment updated.
SortRootCategories created.
Empty places.
One more empty place.
For search view alphabetical order created.
RaisePropertyChanged not in model, but in its' property.
Revert RaisePropertyChanged("Model");
Merge pull request #177 from vmoyseenko/DUI-AddonsInAlphabeticalOrder

DUI: Regular nodes and addons is sorted in alphabetical order.