pgsql: Add the possibility to specify an explicit validator function for

Log Message:
-----------
Add the possibility to specify an explicit validator function for foreign-data
wrappers (similar to procedural languages). This way we don't need to retain
the nearly empty libraries, and we are more free in how to implement the
wrapper API in the future.

Modified Files:
--------------
pgsql/doc/src/sgml:
catalogs.sgml (r2.197 -> r2.198)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/catalogs.sgml?r1=2.197&r2=2.198)
keywords.sgml (r2.22 -> r2.23)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/keywords.sgml?r1=2.22&r2=2.23)
pgsql/doc/src/sgml/ref:
alter_foreign_data_wrapper.sgml (r1.1 -> r1.2)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/alter_foreign_data_wrapper.sgml?r1=1.1&r2=1.2)
create_foreign_data_wrapper.sgml (r1.1 -> r1.2)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_foreign_data_wrapper.sgml?r1=1.1&r2=1.2)
pgsql/src:
Makefile (r1.44 -> r1.45)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/Makefile?r1=1.44&r2=1.45)
pgsql/src/backend/catalog:
information_schema.sql (r1.52 -> r1.53)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/information_schema.sql?r1=1.52&r2=1.53)
pgsql/src/backend/commands:
foreigncmds.c (r1.5 -> r1.6)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/foreigncmds.c?r1=1.5&r2=1.6)
pgsql/src/backend/foreign:
Makefile (r1.1 -> r1.2)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/Makefile?r1=1.1&r2=1.2)
foreign.c (r1.2 -> r1.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/foreign.c?r1=1.2&r2=1.3)
pgsql/src/backend/nodes:
copyfuncs.c (r1.423 -> r1.424)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/copyfuncs.c?r1=1.423&r2=1.424)
equalfuncs.c (r1.347 -> r1.348)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/nodes/equalfuncs.c?r1=1.347&r2=1.348)
pgsql/src/backend/parser:
gram.y (r2.658 -> r2.659)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.658&r2=2.659)
keywords.c (r1.209 -> r1.210)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/keywords.c?r1=1.209&r2=1.210)
pgsql/src/bin/pg_dump:
pg_dump.c (r1.524 -> r1.525)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.c?r1=1.524&r2=1.525)
pg_dump.h (r1.152 -> r1.153)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/pg_dump/pg_dump.h?r1=1.152&r2=1.153)
pgsql/src/bin/psql:
describe.c (r1.200 -> r1.201)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/describe.c?r1=1.200&r2=1.201)
tab-complete.c (r1.179 -> r1.180)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/bin/psql/tab-complete.c?r1=1.179&r2=1.180)
pgsql/src/include/catalog:
catversion.h (r1.523 -> r1.524)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/catversion.h?r1=1.523&r2=1.524)
pg_foreign_data_wrapper.h (r1.2 -> r1.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_foreign_data_wrapper.h?r1=1.2&r2=1.3)
pg_proc.h (r1.536 -> r1.537)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/catalog/pg_proc.h?r1=1.536&r2=1.537)
pgsql/src/include/foreign:
foreign.h (r1.2 -> r1.3)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/foreign/foreign.h?r1=1.2&r2=1.3)
pgsql/src/include/nodes:
parsenodes.h (r1.391 -> r1.392)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/parsenodes.h?r1=1.391&r2=1.392)
pgsql/src/test/regress/expected:
foreign_data.out (r1.6 -> r1.7)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/foreign_data.out?r1=1.6&r2=1.7)
pgsql/src/test/regress/sql:
foreign_data.sql (r1.4 -> r1.5)
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/foreign_data.sql?r1=1.4&r2=1.5)

Removed Files:
-------------
pgsql/src/backend/foreign/dummy:
Makefile
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/dummy/Makefile)
dummy_fdw.c
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/dummy/dummy_fdw.c)
pgsql/src/backend/foreign/postgresql:
Makefile
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/postgresql/Makefile)
postgresql_fdw.c
(http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/foreign/postgresql/postgresql_fdw.c)