Eliminate trivial whitespace inconsistency in docs sample code.
Redo postgres_fdw's planner code so it can handle parameterized paths.

I wasn't going to ship this without having at least some example of how
to do that.  This version isn't terribly bright; in particular it won't
consider any combinations of multiple join clauses.  Given the cost of
executing a remote EXPLAIN, I'm not sure we want to be very aggressive
about doing that, anyway.

In support of this, refactor generate_implied_equalities_for_indexcol
so that it can be used to extract equivalence clauses that aren't
necessarily tied to an index.
Avoid retrieving dummy NULL columns in postgres_fdw.

This should provide some marginal overall savings, since it surely takes
many more cycles for the remote server to deal with the NULL columns than
it takes for postgres_fdw not to emit them.  But really the reason is to
keep the emitted queries from looking quite so silly ...
Change commit_delay to be SUSET for 9.3+
Prior to 9.3 the commit_delay affected only the current user,
whereas now only the group leader waits while holding the
WALWriteLock. Deliberate or accidental settings to a poor
value could seriously degrade performance for all users.
Privileges may be delegated by SECURITY DEFINER functions
for anyone that needs per-user settings in real situations.
Request for change from Peter Geoghegan
Silence compiler warnings about unused values.

Per gripe from Kevin Grittner.
Allow I/O reliability checks using 16-bit checksums

Checksums are set immediately prior to flush out of shared buffers
and checked when pages are read in again. Hint bit setting will
require full page write when block is dirtied, which causes various
infrastructure changes. Extensive comments, docs and README.

WARNING message thrown if checksum fails on non-all zeroes page;
ERROR thrown but can be disabled with ignore_checksum_failure = on.

Feature enabled by an initdb option, since transition from option off
to option on is long and complex and has not yet been implemented.
Default is not to use checksums.

Checksum used is WAL CRC-32 truncated to 16-bits.

Simon Riggs, Jeff Davis, Greg Smith
Wide input and assistance from many community members. Thank you.
Add new README file for pages/checksums
Update commit_delay documentation.

Commit 13fe298ca06f5390df5edf073cf401f9f0b67458 changed this GUC to be
PGC_SUSET, but neglected to update the documentation to match.

While at it, edit and rearrange the text a little for clarity.
Suppress uninitialized-variable warning in new checksum code.

Some compilers understand that this coding is safe, and some don't.
Fix problems with incomplete attempt to prohibit OIDS with MVs.

Problem with assertion failure in restoring from pg_dump output
reported by Joachim Wieland.

Review and suggestions by Tom Lane and Robert Haas.