Teach SPGiST to store nulls and do whole-index scans.

This patch fixes the other major compatibility-breaking limitation of
SPGiST, that it didn't store anything for null values of the indexed
column, and so could not support whole-index scans or "x IS NULL"
tests.  The approach is to create a wholly separate search tree for
the null entries, and use fixed "allTheSame" insertion and search
rules when processing this tree, instead of calling the index opclass
methods.  This way the opclass methods do not need to worry about
dealing with nulls.

Catversion bump is for pg_am updates as well as the change in on-disk
format of SPGiST indexes; there are some tweaks in SPGiST WAL records
as well.

Heavily rewritten version of a patch by Oleg Bartunov and Teodor Sigaev.
(The original also stored nulls separately, but it reused GIN code to do
so; which required undesirable compromises in the on-disk format, and
would likely lead to bugs due to the GIN code being required to work in
two very different contexts.)
Fix documented type of t_infomask2.

Per Koizumi Satoru
Make parameter name consistent with syntax summary.

Thomas Hunger
Make INSERT/UPDATE queries depend on their specific target columns.

We have always created a whole-table dependency for the target relation,
but that's not really good enough, as it doesn't prevent scenarios such
as dropping an individual target column or altering its type.  So we
have to create an individual dependency for each target column, as well.

Per report from Bill MacArthur of a rule containing UPDATE breaking
after such an alteration.  Note that this patch doesn't try to make
such cases work, only to ensure that the attempted ALTER TABLE throws
an error telling you it can't cope with adjusting the rule.

This is a long-standing bug, but given the lack of prior reports
I'm not going to risk back-patching it.  A back-patch wouldn't do
anything to fix existing rules' dependency lists, anyway.
Remove tabs in SGML files
Add comment for missing break in switch

For clarity, following other sites, and to silence Coverity.
Use correct sizeof operand in qsort call

Probably no practical impact, since all pointers ought to have the
same size, but it was wrong nonetheless.  Found by Coverity.
Fix SPGiST vacuum algorithm to handle concurrent tuple motion properly.

A leaf tuple that we need to delete could get moved as a consequence of an
insertion happening concurrently with the VACUUM scan.  If it moves from a
page past the current scan point to a page before, we'll miss it, which is
not acceptable.  Hence, when we see a leaf-page REDIRECT that could have
been made since our scan started, chase down the redirection pointer much
as if we were doing a normal index search, and be sure to vacuum every page
it leads to.  This fixes the issue because, if the tuple was on page N at
the instant we start our scan, we will surely find it as a consequence of
chasing the redirect from page N, no matter how much it moves around in
between.  Problem noted by Takashi Yamamoto.
In pg_upgrade, add various logging improvements:

	add ability to control permissions of created files
	have psql echo its queries for easier debugging
	output four separate log files, and delete them on success
	add -r/--retain option to keep log files after success
	make logs file append-only
	remove -g/-G/-l logging options
	sugggest tailing appropriate log file on failure
	enhance -v/--verbose behavior
pgstattuple: Add new error case for spgist indexes.

Extracted from a larger patch by Jaime Casanova, reviewed by Noah Misch.
I think this error message could use some more extensive revision, but
this at least makes the handling of spgist consistent with what we do for
other types of indexes that this code doesn't know how to handle.
pgstattuple: Use a BufferAccessStrategy object to avoid cache-trashing.

Jaime Casanova, reviewed by Noah Misch, slightly modified by me.
Create a stack of pl/python "execution contexts".

This replaces the former global variable PLy_curr_procedure, and provides
a place to stash per-call-level information.  In particular we create a
per-call-level scratch memory context.

For the moment, the scratch context is just used to avoid leaking memory
from datatype output function calls in PLyDict_FromTuple.  There probably
will be more use-cases in future.

Although this is a fix for a pre-existing memory leakage bug, it seems
sufficiently invasive to not want to back-patch; it feels better as part
of the major rearrangement of plpython code that we've already done as
part of 9.2.

Jan Urbański
Fix minor memory leak in PLy_typeinfo_dealloc().

We forgot to free the per-attribute array element descriptors.

Jan Urbański
Patch some corner-case bugs in pl/python.

Dave Malcolm of Red Hat is working on a static code analysis tool for
Python-related C code.  It reported a number of problems in plpython,
most of which were failures to check for NULL results from object-creation
functions, so would only be an issue in very-low-memory situations.

Patch in HEAD and 9.1.  We could go further back but it's not clear that
these issues are important enough to justify the work.

Jan Urbański
pg_dump: Fix some minor memory leaks

Although we often don't care about freeing all memory in pg_dump,
these functions already freed the same memory in other code paths, so
we might as well do it consistently.

found by Coverity
Add additional safety check against invalid backup label file

It was already checking for invalid data after "BACKUP FROM", but
would possibly crash if "BACKUP FROM" was missing altogether.

found by Coverity
COPY: Add an assertion

This is for tools such as Coverity that don't know that the grammar
enforces that the case of not having a relation (but instead a query)
cannot happen in the FROM case.
Add missing va_end() calls

found by Coverity
Improve EncodeDateTime and EncodeTimeOnly APIs

Use an explicit argument to tell whether to include the time zone in
the output, rather than using some undocumented pointer magic.
Uppercase pg_upgrade status output title.