pgsql: Revert timeline following in replication slots

Revert timeline following in replication slots

This reverts commits f07d18b6e94d, 82c83b337202, 3a3b309041b0, and
24c5f1a103ce.

This feature has shown enough immaturity that it was deemed better to
rip it out before rushing some more fixes at the last minute.  There are
discussions on larger changes in this area for the next release.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/c1543a81a7a89207b6c45b8f3f7f07b1148fcc6e

Modified Files
--------------
src/backend/access/transam/xlogreader.c            |   9 -
src/backend/access/transam/xlogutils.c             | 212 +-------------
src/backend/replication/logical/logicalfuncs.c     |  12 +-
src/include/access/xlogreader.h                    |  18 --
src/test/modules/Makefile                          |   1 -
src/test/modules/test_slot_timelines/.gitignore    |   3 -
src/test/modules/test_slot_timelines/Makefile      |  22 --
src/test/modules/test_slot_timelines/README        |  19 --
.../expected/load_extension.out                    |  19 --
.../expected/load_extension_1.out                  |   7 -
.../test_slot_timelines/sql/load_extension.sql     |   7 -
.../test_slot_timelines--1.0.sql                   |  16 --
.../test_slot_timelines/test_slot_timelines.c      | 133 ---------
.../test_slot_timelines/test_slot_timelines.conf   |   2 -
.../test_slot_timelines.control                    |   5 -
src/test/recovery/Makefile                         |   2 -
.../recovery/t/006_logical_decoding_timelines.pl   | 307 ---------------------
17 files changed, 21 insertions(+), 773 deletions(-)