Improve commentary in match_pathkeys_to_index().

For a little while there I thought match_pathkeys_to_index() was broken
because it wasn't trying to match index columns to pathkeys in order.
Actually that's correct, because GiST can support ordering operators
on any random collection of index columns, but it sure needs a comment.
backend: Fix minor memory leak in configuration file processing

Just for consistency with the other code paths.

found by Coverity
pg_restore: Fix memory and file descriptor leak with directory format

found by Coverity
pg_dump: Fix crash with invalid pg_cast row

An invalid combination of pg_cast.castfunc and pg_cast.castmethod
would result in a segmentation fault.  Now it prints a warning.

found by Coverity
psql: Remove inappropriate const qualifiers

Since mbvalidate() can alter the string it validates, having the
callers claim that the strings they accept are const is inappropriate.
libpq: Fix minor memory leaks

When using connection info arrays with a conninfo string in the dbname
slot, some memory would be leaked if an error occurred while
processing the following array slots.

found by Coverity
In pg_upgrade, create a script to incrementally generate more accurate
optimizer statistics so the cluster can be made available sooner.
Add note about column privilege behavior to REVOKE reference page

suggested by Josh Berkus
In pg_upgrade, move new echo quote define into include file.
Honor inputdir and outputdir when converting regression files.

When converting source files, pg_regress' inputdir and outputdir options were
ignored when computing the locations of the destination files. In consequence,
these options were effectively unusable when the regression inputs need to
be adjusted by pg_regress. This patch makes pg_regress put the converted files
in the same place that these options specify non-converted input or results
files are to be found. Backpatched to all live branches.
In pg_upgrade, remove dependency on pg_config, as that might not be in
the non-development install.  Instead, use the LOAD mechanism to check
for the pg_upgrade_support shared object, like we do for other shared
object checks.

Backpatch to 9.1.

Report from Àlvaro
plperl: Package-qualify _TD

Failing to do so causes trigger invocation to fail when they are nested
within a function invocation that changes the current package.

Backpatch to 9.1; previous releases used a different method to obtain
_TD.  Per bug report from Mark Murawski (bug #6511)

Author: Alex Hunsaker
pg_dump: fix double free of query results

This bug was introduced while refactoring in commit 1631598e --- no need
to back-patch.

Bug report and fix from Joachim Wieland.
Restructure SELECT INTO's parsetree representation into CreateTableAsStmt.

Making this operation look like a utility statement seems generally a good
idea, and particularly so in light of the desire to provide command
triggers for utility statements.  The original choice of representing it as
SELECT with an IntoClause appendage had metastasized into rather a lot of
places, unfortunately, so that this patch is a great deal more complicated
than one might at first expect.

In particular, keeping EXPLAIN working for SELECT INTO and CREATE TABLE AS
subcommands required restructuring some EXPLAIN-related APIs.  Add-on code
that calls ExplainOnePlan or ExplainOneUtility, or uses
ExplainOneQuery_hook, will need adjustment.

Also, the cases PREPARE ... SELECT INTO and CREATE RULE ... SELECT INTO,
which formerly were accepted though undocumented, are no longer accepted.
The PREPARE case can be replaced with use of CREATE TABLE AS EXECUTE.
The CREATE RULE case doesn't seem to have much real-world use (since the
rule would work only once before failing with "table already exists"),
so we'll not bother with that one.

Both SELECT INTO and CREATE TABLE AS still return a command tag of
"SELECT nnnn".  There was some discussion of returning "CREATE TABLE nnnn",
but for the moment backwards compatibility wins the day.

Andres Freund and Tom Lane
pg_dump: Remove undocumented "files" output format

This was for demonstration only, and now it was creating compiler
warnings from zlib without an obvious fix (see also
d923125b77c5d698bb8107a533a21627582baa43), let's just remove it.  The
"directory" format is presumably similar enough anyway.
pg_upgrade: Add new generated file to .gitignore
Remove stray word from sepgsql documentation.
Update struct Trigger in docs
Fix trigger example code to match header changes

I should have done this in b93f5a5673b4bb09e14eb80fe28aa21fc20a6271 but
didn't notice the problem at the time.

Per report from Marco Nenciarini
pg_dump: get rid of die_horribly

The old code was using exit_horribly or die_horribly other depending on
whether it had an ArchiveHandle on which to close the connection or not;
but there were places that were passing a NULL ArchiveHandle to
die_horribly, and other places that used exit_horribly while having an
AH available.  So there wasn't all that much consistency.

Improve the situation by keeping only one of the routines, and instead
of having to pass the AH down from the caller, arrange for it to be
present for an on_exit_nicely callback to operate on.

Author: Joachim Wieland
Some tweaks by me

Per a suggestion from Robert Haas, in the ongoing "parallel pg_dump"
saga.