pgsql: Add idle_in_transaction_session_timeout.

Add idle_in_transaction_session_timeout.

Vik Fearing, reviewed by Stéphane Schildknecht and me, and revised
slightly by me.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/c6dda1f48e573cc60fe25d8d470a05bfabed0252

Modified Files
--------------
doc/src/sgml/config.sgml                      | 20 +++++++++++++
doc/src/sgml/mvcc.sgml                        |  4 ++-
src/backend/storage/lmgr/proc.c               |  1 +
src/backend/tcop/postgres.c                   | 42 +++++++++++++++++++++++++--
src/backend/utils/errcodes.txt                |  1 +
src/backend/utils/init/globals.c              |  1 +
src/backend/utils/init/postinit.c             | 10 +++++++
src/backend/utils/misc/guc.c                  | 11 +++++++
src/backend/utils/misc/postgresql.conf.sample |  1 +
src/include/miscadmin.h                       |  1 +
src/include/storage/proc.h                    |  1 +
src/include/utils/timeout.h                   |  1 +
12 files changed, 91 insertions(+), 3 deletions(-)