Add cost estimation of range @> and <@ operators.

The estimates are based on the existing lower bound histogram, and a new
histogram of range lengths.

Bump catversion, because the range length histogram now needs to be present
in statistic slot kind 6, or you get an error on @> and <@ queries. (A
re-ANALYZE would be enough to fix that, though)

Alexander Korotkov, with some refactoring by me.
Change the way UESCAPE is lexed, to reduce the size of the flex tables.

The error rule used to avoid backtracking with the U&'...' UESCAPE 'x'
syntax bloated the flex tables, so refactor that. This patch makes the error
rule shorter, by introducing a new exclusive flex state that's entered after
parsing U&'...'. This shrinks the postgres binary by about 220kB.
Avoid inserting Result nodes that only compute identity projections.

The planner sometimes inserts Result nodes to perform column projections
(ie, arbitrary scalar calculations) above plan nodes that lack projection
logic of their own.  However, we did that even if the lower plan node was
in fact producing the required column set already; which is a pretty common
case given the popularity of "SELECT * FROM ...".  Measurements show that
the useless plan node adds non-negligible overhead, especially when there
are many columns in the result.  So add a check to avoid inserting a Result
node unless there's something useful for it to do.

There are a couple of remaining places where unnecessary Result nodes
could get inserted, but they are (a) much less performance-critical,
and (b) coded in such a way that it's hard to avoid inserting a Result,
because the desired tlist is changed on-the-fly in subsequent logic.
We'll leave those alone for now.

Kyotaro Horiguchi; reviewed and further hacked on by Amit Kapila and
Tom Lane.
Minor fixes for hstore_to_json_loose().

Fix unportable use of isdigit(), get rid of useless calculations.
Also update psqlscan.l with the UESCAPE error rule changes.

Even though this patch had no user-visible difference, better keep the code
in psqlscan.l sync with the backend lexer. And of course it's nice to shrink
the psql binary, too. Ecpg's version of the lexer doesn't have the error
rule, it doesn't try to avoid backing up, so it doesn't need to be modified.

As reminded by Tom Lane
Add regression test for MV join to view.

This would have caught a bug in the initial patch, and seems like
a good thing to test going forward.

Per bug report by Erik Rijkers and fix by Tom Lane
Revert unnecessary change in MV call to checkRuleResultList().

Due to a misreading of the function's comment block, there was an
unneeded change to a call in rewriteDefine.c.  There is, in fact
no reason to pass false for a MV; it should be true just like a
view.

Fixes issue pointed out by Tom Lane
Avoid inserting no-op Limit plan nodes.

This was discussed in connection with the patch to avoid inserting no-op
Result nodes, but not actually implemented therein.
Extend format() to handle field width and left/right alignment.

This change adds some more standard sprintf() functionality to format().

Pavel Stehule, reviewed by Dean Rasheed and Kyotaro Horiguchi