WIP: generate types and methods using GObject introspection

I've been experimenting a bit with auto-generating types and method wrapping using GObject-Introspection. This should fix many of the ccalls for us so that we can focus on create Julian wrappers. (is that the adjective for idiomatic julia?) 

It is far from ready to merge yet (I have patched it in among the existing wrappers in quite an ugly way IMHO, and it currently leaks refs and strings like it's no tomorrow) but I'd like to discuss and settle on a consistent naming schemes. Should we have Gtk.Window or Gtk.GtkWindow, Clutter.Actor or ClutterActor? I tend to prefer the former as the primary names. Same questing with constants/Enums (not implemented yet) as Gobject-Introspection allows constants starting with numbers.