[Nautilus-list] shared library tree view is now default

[Maciej Stachowiak <mjs eazel com>]

I made the shlib version of the tree view the default. If this causes
you an problems, you can revert to the exe version with
--enable-tree-view-exe-server.

The one problem that I know I introduced is NautilusDirectory leaks. I
tried my best to fix all the ones I could, but I'm not sure where the
rest are coming from. I would appreciate help with this.

 - Maciej