Move GtkStateFlags constants into top-level
ljglibs work: Massive additions

Add support for inheritance (glib class hiearchies).

Add new basic ctypes:

- gio.Application
- gobject.Object
- gobject.Type
- gtk.Application
- gtk.Bin
- gtk.Container
- gtk.EventBox
- gtk.Widget

Also add signal support, Lua style. Does not mimic the gobject API that much,
but for good reason. Has support for weakly refed handlers, which is a must
for correctly dealing with GC.