Fix docs on lock level for ALTER TABLE VALIDATE

ALTER TABLE .. VALIDATE CONSTRAINT previously
gave incorrect details about lock levels and
therefore incomplete reasons to use the option.

Initial bug report and fix from Marko Tiikkaja
Reworded by me to include comments by Kevin Grittner
Merge branch 'master' into filter
Fix the create_index regression test for Danish collation.

In Danish collations, there are letter combinations which sort
higher than 'Z'.  A test for values > 'WA' was picking up rows
where the value started with 'AA', causing the test to fail.

Backpatch to 9.2, where the failing test was added.

Per report from Svenne Krap and analysis by Jeff Janes
Modernize entab source code
Remove halt.c, improve comments, rename manual page file.
Merge branch 'master' into filter
Support TB (terabyte) memory unit in GUC variables.

Patch by Simon Riggs, reviewed by Jeff Janes and me.
initdb: Add blank line before output about checksums

This maintains the logical grouping of the output better.
Further update CREATE FUNCTION documentation about argument names

More languages than SQL and PL/pgSQL actually support parameter names.
Merge branch 'master' into filter