plproxy - plproxy: More flexible CONNECT function.

Log Message:
-----------
More flexible CONNECT function.

It allows CONNECT to take function arguments or do function calls:

    CONNECT func(..);
    CONNECT argname;
    CONNECT $argnum;

NB: giving untrusted users ability to specify full connect string creates
security hole.  Eg it can real cleartext passwords from .pgpass/pg_service.
If such function cannot be avoided, it's access rights need to be restricted.

Patch by Ian Sollars

Modified Files:
--------------
    plproxy/src:
        cluster.c (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/cluster.c?r1=1.7&r2=1.8)
        function.c (r1.6 -> r1.7)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/function.c?r1=1.6&r2=1.7)
        parser.y (r1.14 -> r1.15)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/parser.y?r1=1.14&r2=1.15)
        plproxy.h (r1.15 -> r1.16)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/src/plproxy.h?r1=1.15&r2=1.16)
    plproxy/sql:
        plproxy_test.sql (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/sql/plproxy_test.sql?r1=1.7&r2=1.8)
    plproxy/expected:
        plproxy_test.out (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/plproxy/plproxy/expected/plproxy_test.out?r1=1.7&r2=1.8)