pgsql: Add constraint exclusion items: < > * Allow EXPLAIN to identify

Log Message:
-----------
Add constraint exclusion items:
<

* Allow EXPLAIN to identify tables that were skipped because of
enable_constraint_exclusion
* Allow EXPLAIN output to be more easily processed by scripts

760a763

* Allow enable_constraint_exclusion to work for UPDATE and DELETE queries

Modified Files:
--------------
pgsql/doc:
TODO (r1.1609 -> r1.1610)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.1609&amp;r2=1.1610)
pgsql/doc/src/FAQ:
TODO.html (r1.116 -> r1.117)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.116&amp;r2=1.117)