options for RAISE statement

Hello

this patch adds possibility to set additional options (SQLSTATE,
DETAIL, DETAIL_LOG and HINT) for RAISE statement,

Proposal: http://archives.postgresql.org/pgsql-hackers/2008-04/msg00919.php

I changed keyword from WITH to USING, because I don't would to create
new keyword

RAISE level 'format' [, expression [, ...]] [ USING ( option =
expression [, ... ] ) ];

RAISE EXCEPTION 'Nonexistent ID --> %', user_id
  USING (hint = 'Please, check your user id');

Regards
Pavel Stehule