This adds a support for receiving samples over unix domain socket.
It's a better alternative to the SHM refclock, the resolution is not
limited to microseconds and it doesn't require polling.
This is a verbatim copy of the files at that stage of the repository that was
built from the CVS import. It allows future development to see a bit of recent
history, but without carrying around the baggage going back to 1997. If that
is really required, git grafts can be used.
