Prevent edited items to be opened.
Fix disappearing text in directory list.
Fix MainWindow not closing bug.

Also added a behavior to not break the project file.
Implemented name editing.

Still has some bugs and the input isn't validated.
Fixed main window state restore.
Some code cleanup...
Fixed text editing
Some code cleanup...
Use ListCollectionViewSource's edit mechanisms.
Enable virtualization again to improve performence.
Remove SortEntries.