pgsql: Add support for temporary replication slots

Add support for temporary replication slots

This allows creating temporary replication slots that are removed
automatically at the end of the session or on error.

From: Petr Jelinek <petr(dot)jelinek(at)2ndquadrant(dot)com>

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/a924c327e2793d2025b19e18de7917110dc8afd8

Modified Files
--------------
contrib/test_decoding/Makefile | 2 +-
contrib/test_decoding/expected/ddl.out | 4 +-
contrib/test_decoding/expected/slot.out | 58 +++++++++++++++++++++++++++
contrib/test_decoding/sql/slot.sql | 20 ++++++++++
doc/src/sgml/func.sgml | 16 ++++++--
doc/src/sgml/protocol.sgml | 13 ++++++-
src/backend/catalog/system_views.sql | 11 ++++++
src/backend/replication/repl_gram.y | 22 +++++++----
src/backend/replication/repl_scanner.l | 1 +
src/backend/replication/slot.c | 69 ++++++++++++++++++++++++++-------
src/backend/replication/slotfuncs.c | 24 ++++++++----
src/backend/replication/walsender.c | 28 +++++++------
src/backend/storage/lmgr/proc.c | 3 ++
src/backend/tcop/postgres.c | 3 ++
src/include/catalog/pg_proc.h | 6 +--
src/include/nodes/replnodes.h | 1 +
src/include/replication/slot.h | 4 +-
src/test/regress/expected/rules.out | 3 +-
18 files changed, 237 insertions(+), 51 deletions(-)