Fix plpython's handling of functions used as triggers on multiple tables.

plpython tried to use a single cache entry for a trigger function, but it
needs a separate cache entry for each table the trigger is applied to,
because there is table-dependent data in there.  This was done correctly
before 9.1, but commit 46211da1b84bc3537e799ee1126098e71c2428e8 broke it
by simplifying the lookup key from "function OID and triggered table OID"
to "function OID and is-trigger boolean".  Go back to using both OIDs
as the lookup key.  Per bug report from Sandro Santilli.

Andres Freund
doc:  revert 80c20fcf3df17309b3c131962045825f42e45bc7 and
0e93959a70ac6e7c7858d1d6fb00645e7540a1cc

Revert patch that modified doc index mentions of search_path

Per Peter E.
Merge branch 'master' of /home/kgrittn/pg/postgresql into matview
Allow CREATE TABLE IF EXIST so succeed if the schema is nonexistent

Previously, CREATE TABLE IF EXIST threw an error if the schema was
nonexistent.  This was done by passing 'missing_ok' to the function that
looks up the schema oid.
Issue ERROR if FREEZE mode can't be honored by COPY

Previously non-honored FREEZE mode was ignored.  This also issues an
appropriate error message based on the cause of the failure, per
suggestion from Tom.  Additional regression test case added.
Update LookupExplicitNamespace() comments;  commit message update

Also, commit 7e2322dff30c04d90c0602d2b5ae24b4881db88b affected DROP
TABLE IF EXISTS, not CREATE TABLE IF EXISTS.
Update comments in new DROP IF EXISTS code; commit message update

DROP IF EXISTS with a missing schema in commit
7e2322dff30c04d90c0602d2b5ae24b4881db88b applies not only to tables, but
to DROP IF EXISTS with missing schemas for indexes, views, sequences,
and foreign tables.  Yeah!
Make LATERAL implicit for functions in FROM.

The SQL standard does not have general functions-in-FROM, but it does
allow UNNEST() there (see the <collection derived table> production),
and the semantics of that are defined to include lateral references.
So spec compliance requires allowing lateral references within UNNEST()
even without an explicit LATERAL keyword.  Rather than making UNNEST()
a special case, it seems best to extend this flexibility to any
function-in-FROM.  We'll still allow LATERAL to be written explicitly
for clarity's sake, but it's now a noise word in this context.

In theory this change could result in a change in behavior of existing
queries, by allowing what had been an outer reference in a function-in-FROM
to be captured by an earlier FROM-item at the same level.  However, all
pre-9.3 PG releases have a bug that causes them to match variable
references to earlier FROM-items in preference to outer references (and
then throw an error).  So no previously-working query could contain the
type of ambiguity that would risk a change of behavior.

Per a suggestion from Andrew Gierth, though I didn't use his patch.
Made ecpglib use translated messages.

Bug reported and fixed by Chen Huajun <chenhj@cn.fujitsu.com>.
Handle SPIErrors raised directly in PL/Python code.

If a PL/Python function raises an SPIError (or one if its subclasses)
directly with python's raise statement, treat it the same as an SPIError
generated internally. In particular, if the user sets the sqlstate
attribute, preserve that.

Oskari Saarenmaa and Jan Urbański, reviewed by Karl O. Pinc.
Merge branch 'master' into matview