Replication toolkit added to repository

I've committed contrib/rserv/ which provides replication capabilities to
PostgreSQL. The code was developed by Vadim, with some script and
wrapper support from myself. The current version has been tested under
Linux only, though I know of no reason why it won't work elsewhere.
Requires PostgreSQL, perl5, and (for a demo gui) tcl/tk.

The current package will replicate one master to one slave, though there
are some hooks already in place to support multiple slaves. I'll add
that as time permits, or others are welcome to dive in and send patches
;)

The package as-committed requires PostgreSQL-7.1 (appropriate because it
is in the 7.1 tree), but the code can be built on 7.0.x given a
different Makefile. The compiled code works with both through the magic
of #ifdef. I've got a standalone Makefile for 7.0.x and earlier, and can
post it if desired. Also, I could use some advice on how to build extra
modules such as this from an rpm-managed PostgreSQL installation. Can it
actually work? If so, where do the makefiles hide?

Have fun :)

- Thomas