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)