ContainsMember added to SearchCategory.
OnSubClassesPanelKeyDown moved in LibraryWrapPanel, and was renamed into OnLibraryWrapPanelKeyDown
FindFirstChildListItem added.
In FindFirstChildListItem removed generic class.
Remove excess namespace.
Merge branch 'DUI-KeyNavigation(fromMemberGroup-to-ClassList)' into DUI-KeyNavigation(fromCategory-to-Category)