Improve SPI documentation about null-flags arrays.

Clarify the description of nulls[] arguments, and use the same wording
for all SPI functions with this type of argument.  Per gripe from Yuriy
Rusinov.
9.3 release notes:  add markup for text

Still need to add links for new features.
9.3 release notes:  Add links to SGML sections
9.3 release notes:  Add markup for pg_backup_start_time()
9.3 release notes:  move compatibility items into their own section
9.3 release notes:  adjustments

Fixes from Peter Geoghegan, Ian Lawrence Barwick, Marti Raudsepp
docs:  fix log_line_prefix session id docs

Backpatch to 9.2.

Report from Ian Lawrence Barwick
9.3 docs:  wording fixes

From Erik Rijkers
docs:  log_line_prefix session id fix

Restore 4-byte designation for docs.  Fix 9.3 doc query to properly pad
to four digits.

Backpatch to all active branches

Per suggestions from Ian Lawrence Barwick
docs:  Improve log_line_prefix session_id query
Improve behavior of \watch with non-tuple-returning commands.

Print the command tag if we get PGRES_COMMAND_OK, and throw an error for
other cases.  Per gripe from Michael Paquier.

In passing, add an fflush(), just to be real sure the output appears
before we sleep.
Translation updates
Revert idea of zer-padding padding session id in log_line_prefix

Removal of doc adjustment and release note mention as well.
Execute SET TRANSACTION SNAPSHOT during pg_dump
Previous coding set the SQL buffer but never executed

Bug noted by me during beta testing
9.3 release notes:  update from Amit Kapila

No need to mention wal_receiver_status_interval.
9.3 release notes: Add cache of local locks

Mention this also helps in the restoring of pg_dumps.

Jeff Janes
9.3 release notes:  use "restoration"

Andrew Dunstan
Disallow unlogged materialized views.

The initial implementation of this feature was really unsupportable,
because it's relying on the physical size of an on-disk file to carry the
relation's populated/unpopulated state, which is at least a modularity
violation and could have serious long-term consequences.  We could say that
an unlogged matview goes to empty on crash, but not everybody likes that
definition, so let's just remove the feature for 9.3.  We can add it back
when we have a less klugy implementation.

I left the grammar and tab-completion support for CREATE UNLOGGED
MATERIALIZED VIEW in place, since it's harmless and allows delivering a
more specific error message about the unsupported feature.

I'm committing this separately to ease identification of what should be
reverted when/if we are able to re-enable the feature.
Back out some recent translation updates.

Very old versions of msgfmt choke on these specific messages, for reasons
that are unclear at the moment.  Remove them so that we can ship a beta
release and not get complaints from testers (these messages will just go
untranslated, instead, and we're hardly at 100% coverage anyway).
Peter Eisentraut will look for a better fix later.
Move materialized views' is-populated status into their pg_class entries.

Previously this state was represented by whether the view's disk file had
zero or nonzero size, which is problematic for numerous reasons, since it's
breaking a fundamental assumption about heap storage.  This was done to
allow unlogged matviews to revert to unpopulated status after a crash
despite our lack of any ability to update catalog entries post-crash.
However, this poses enough risk of future problems that it seems better to
not support unlogged matviews until we can find another way.  Accordingly,
revert that choice as well as a number of existing kluges forced by it
in favor of creating a pg_class.relispopulated flag column.