Issue: Add a navigation widget to cater to large numbers of categories and wikis

The number of articles and categories on my site is getting to the degree where its getting hard to navigate. The standard wiki links navigation is nice, but it does not provide an overview of articles and specialpages:all pages and specialpages:allcategories also do not provide a nice way for users to browse articles.

I suggestion a treeview navigation widget that allow a user to go trough all categories and underlying articles.