pgsql-server: Invent WAL timelines, as per recent discussion, to make

Log Message:
-----------
Invent WAL timelines, as per recent discussion, to make point-in-time
recovery more manageable. Also, undo recent change to add FILE_HEADER
and WASTED_SPACE records to XLOG; instead make the XLOG page header
variable-size with extra fields in the first page of an XLOG file.
This should fix the boundary-case bugs observed by Mark Kirkwood.
initdb forced due to change of XLOG representation.

Modified Files:
--------------
pgsql-server/doc/src/sgml:
page.sgml (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/doc/src/sgml/page.sgml.diff?r1=1.17&r2=1.18)
pgsql-server/src/backend/access/heap:
heapam.c (r1.170 -> r1.171)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/heap/heapam.c.diff?r1=1.170&r2=1.171)
pgsql-server/src/backend/access/nbtree:
nbtinsert.c (r1.112 -> r1.113)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/nbtree/nbtinsert.c.diff?r1=1.112&r2=1.113)
nbtpage.c (r1.76 -> r1.77)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/nbtree/nbtpage.c.diff?r1=1.76&r2=1.77)
nbtsort.c (r1.84 -> r1.85)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/nbtree/nbtsort.c.diff?r1=1.84&r2=1.85)
nbtxlog.c (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/nbtree/nbtxlog.c.diff?r1=1.15&r2=1.16)
pgsql-server/src/backend/access/transam:
recovery.conf.sample (r1.2 -> r1.3)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/transam/recovery.conf.sample.diff?r1=1.2&r2=1.3)
rmgr.c (r1.13 -> r1.14)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/transam/rmgr.c.diff?r1=1.13&r2=1.14)
slru.c (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/transam/slru.c.diff?r1=1.17&r2=1.18)
xlog.c (r1.149 -> r1.150)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/transam/xlog.c.diff?r1=1.149&r2=1.150)
xlogutils.c (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/access/transam/xlogutils.c.diff?r1=1.31&r2=1.32)
pgsql-server/src/backend/commands:
sequence.c (r1.113 -> r1.114)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/sequence.c.diff?r1=1.113&r2=1.114)
tablecmds.c (r1.121 -> r1.122)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/tablecmds.c.diff?r1=1.121&r2=1.122)
vacuum.c (r1.283 -> r1.284)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/vacuum.c.diff?r1=1.283&r2=1.284)
vacuumlazy.c (r1.42 -> r1.43)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/commands/vacuumlazy.c.diff?r1=1.42&r2=1.43)
pgsql-server/src/backend/postmaster:
pgarch.c (r1.1 -> r1.2)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/postmaster/pgarch.c.diff?r1=1.1&r2=1.2)
pgsql-server/src/backend/storage/lmgr:
deadlock.c (r1.28 -> r1.29)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/backend/storage/lmgr/deadlock.c.diff?r1=1.28&r2=1.29)
pgsql-server/src/bin/pg_controldata:
pg_controldata.c (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/bin/pg_controldata/pg_controldata.c.diff?r1=1.17&r2=1.18)
pgsql-server/src/bin/pg_resetxlog:
pg_resetxlog.c (r1.20 -> r1.21)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/bin/pg_resetxlog/pg_resetxlog.c.diff?r1=1.20&r2=1.21)
pgsql-server/src/include/access:
xact.h (r1.65 -> r1.66)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/xact.h.diff?r1=1.65&r2=1.66)
xlog.h (r1.53 -> r1.54)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/xlog.h.diff?r1=1.53&r2=1.54)
xlogdefs.h (r1.11 -> r1.12)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/xlogdefs.h.diff?r1=1.11&r2=1.12)
xlogutils.h (r1.14 -> r1.15)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/xlogutils.h.diff?r1=1.14&r2=1.15)
pgsql-server/src/include/catalog:
pg_control.h (r1.15 -> r1.16)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/catalog/pg_control.h.diff?r1=1.15&r2=1.16)
pgsql-server/src/include/storage:
bufpage.h (r1.59 -> r1.60)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/storage/bufpage.h.diff?r1=1.59&r2=1.60)

Added Files:
-----------
pgsql-server/src/include/access:
xlog_internal.h (r1.1)
(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/include/access/xlog_internal.h?rev=1.1&content-type=text/x-cvsweb-markup)