plproxy - plproxy: Enable pl/proxy clusters to be defined by SQL/MED

Log Message:
-----------
Enable pl/proxy clusters to be defined by SQL/MED facilities.
Provide a plproxy foreign data wrapper and a function for
validating cluster definitions. It is still possible to define
clusters using configuration functions, however SQL/MED cluster
definition takes precedence if available.

Modified Files:
--------------
    plproxy:
        Makefile (r1.40 -> r1.41)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/Makefile?r1=1.40&r2=1.41)
    plproxy/doc:
        config.txt (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/doc/config.txt?r1=1.7&r2=1.8)
        todo.txt (r1.11 -> r1.12)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/doc/todo.txt?r1=1.11&r2=1.12)
        tutorial.txt (r1.4 -> r1.5)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/doc/tutorial.txt?r1=1.4&r2=1.5)
    plproxy/src:
        cluster.c (r1.9 -> r1.10)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/cluster.c?r1=1.9&r2=1.10)
        main.c (r1.6 -> r1.7)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/main.c?r1=1.6&r2=1.7)
        plproxy.h (r1.17 -> r1.18)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/plproxy.h?r1=1.17&r2=1.18)

Added Files:
-----------
    plproxy:
        plproxy_fdw.sql (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/plproxy_fdw.sql?rev=1.1&content-type=text/x-cvsweb-markup)
        plproxy_lang.sql (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/plproxy_lang.sql?rev=1.1&content-type=text/x-cvsweb-markup)

Removed Files:
-------------
    plproxy:
        plproxy.sql.in
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/plproxy.sql.in)