Re: pgsql: Various documentation improvements.

Log Message:
-----------
Various documentation improvements. Add a lot of index entries for
the builtin functions (although some more entries are still needed),
and remove the duplicate index entries that have been causing
collateindex.pl warnings. Consistently use "int" and "bigint", rather
than a mix of "int", "integer", "int4", "bigint", and "int8". Make
parenthesis style in syntax examples more consistent. Various
copy-editing for newly-added documentation and SGML markup fixes.

Modified Files:
--------------
pgsql/doc/src/sgml:
dfunc.sgml (r1.31 -> r1.32)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/dfunc.sgml.diff?r1=1.31&r2=1.32)
func.sgml (r1.284 -> r1.285)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.284&r2=1.285)
plpgsql.sgml (r1.75 -> r1.76)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/plpgsql.sgml.diff?r1=1.75&r2=1.76)
xfunc.sgml (r1.103 -> r1.104)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/xfunc.sgml.diff?r1=1.103&r2=1.104)

Neil Conway wrote:
> Consistently use "int" and "bigint", rather than a mix of "int",
> "integer", "int4", "bigint", and "int8".

I should clarify that I just fixed up type names used in the "Functions
and Operators" chapter (e.g. in the tables containing function
descriptions), not in the rest of the documentation.

-Neil