client & server recode

I have made some changes to your vlc-sync extension. Please could you review and pull the changes?

Rough list of changes:
- client now has dialog to enter server IP and port.
- timing now done using callbacks and os.date (should work on most platforms).
- pause/play now synced.
- osd used to give sync information to user.

Known bugs:
- if previous connection attempts have failed and vlc did not exit cleanly listen_tcp/accept may not succeed (workaround: kill all vlc instances and retry)
- get a keep alive warning when sync-server is waiting for client to connect (workaround: ignore it)
- client will crash if server exits abnormally (workaround: restart vlc)

Best regards,
sj