[libvirt] [ocaml] event registration APis v3

Hi, Here are my latest patches which add OCaml bindings for the libvirt event API. I'm pretty happy with them now: my test programs have been running for long periods of time without incident. Changes from the previous submission (sent 2013-04-17) * added a patch which removes the backwards compatability logic from the bindings. The aim is to make the bindings simpler to read and develop. Changes from the initial submission (sent 2013-03-27) * add support for 'deregister_any' * fix the ordering of '{enter,leave}_blocking_section' and GC registration * add timer callbacks Cheers, Dave