Fix tree controller's -visibleForumExpandedAtIndexPath:

Need to check whether its children are hidden, not whether it's hidden itself.
Update forum list for iOS 7.

There are now two different table view cells: one for the favorite forums
section and one for the rest. The cells use auto layout and match @ridilla's
mockups.
Fix selecting forums when there are no favorites.
Hide category-less forums from the forums list.

This can happen if a thread is visited that lives in a forum that, for whatever
reason, doesn't appear in the usual dropdown list of forums.
Xcode dickery.
Remove "first tab" setting.

It'll be replaced with state restoration.
Move Leper's Colony out to basement/tab bar.
Remove old tab bar.
Remove unused #import.