pgsql: Add postgres_fdw contrib module.

Add postgres_fdw contrib module.

There's still a lot of room for improvement, but it basically works,
and we need this to be present before we can do anything much with the
writable-foreign-tables patch. So let's commit it and get on with testing.

Shigeru Hanada, reviewed by KaiGai Kohei and Tom Lane

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/d0d75c402217421b691050857eb3d7af82d0c770

Modified Files
--------------
contrib/Makefile | 1 +
contrib/postgres_fdw/.gitignore | 4 +
contrib/postgres_fdw/Makefile | 27 +
contrib/postgres_fdw/connection.c | 581 +++++++++
contrib/postgres_fdw/deparse.c | 1104 ++++++++++++++++
contrib/postgres_fdw/expected/postgres_fdw.out | 704 +++++++++++
contrib/postgres_fdw/option.c | 293 +++++
contrib/postgres_fdw/postgres_fdw--1.0.sql | 18 +
contrib/postgres_fdw/postgres_fdw.c | 1400 +++++++++++++++++++++
contrib/postgres_fdw/postgres_fdw.control | 5 +
contrib/postgres_fdw/postgres_fdw.h | 52 +
contrib/postgres_fdw/sql/postgres_fdw.sql | 272 ++++
doc/src/sgml/client-auth.sgml | 2 +-
doc/src/sgml/contrib.sgml | 1 +
doc/src/sgml/dblink.sgml | 26 +-
doc/src/sgml/filelist.sgml | 1 +
doc/src/sgml/libpq.sgml | 2 +-
doc/src/sgml/postgres-fdw.sgml | 325 +++++
doc/src/sgml/queries.sgml | 2 +-
doc/src/sgml/recovery-config.sgml | 3 +-
doc/src/sgml/ref/create_foreign_data_wrapper.sgml | 8 -
doc/src/sgml/ref/create_foreign_table.sgml | 12 +-
doc/src/sgml/ref/create_server.sgml | 22 +-
doc/src/sgml/ref/grant.sgml | 7 +-
doc/src/sgml/ref/pg_isready.sgml | 3 +-
doc/src/sgml/ref/psql-ref.sgml | 9 +-
doc/src/sgml/runtime.sgml | 2 +-
src/backend/foreign/foreign.c | 8 +-
28 files changed, 4839 insertions(+), 55 deletions(-)