Added tests for undo/redo operations on implicit and explicit lists.
Fixed bug where explicit collection was not handled correctly when resetting a XamlProperty.
Added tests for undo/redo operations on implicit and explicit dictionaries.
Added tests for clearing explicit lists and dictionaries.
Fixed so an IDictionary item is removed using the item key.
Merge remote-tracking branch 'remotes/origin/WpfDesignerCollectionUndoFix'