pgsql: Add two new format fields for use with to_char(), to_date() and

Log Message:
-----------
Add two new format fields for use with to_char(), to_date() and
to_timestamp():
- ID for day-of-week
- IDDD for day-of-year

This makes it possible to convert ISO week dates to and from text
fully represented in either week ('IYYY-IW-ID') or day-of-year
('IYYY-IDDD') format.

I have also added an 'isoyear' field for use with extract / date_part.

Brendan Jurd

Modified Files:
--------------
pgsql/doc/src/sgml:
func.sgml (r1.358 -> r1.359)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/func.sgml.diff?r1=1.358&r2=1.359)
pgsql/src/backend/utils/adt:
date.c (r1.127 -> r1.128)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/date.c.diff?r1=1.127&r2=1.128)
datetime.c (r1.175 -> r1.176)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/datetime.c.diff?r1=1.175&r2=1.176)
formatting.c (r1.124 -> r1.125)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/formatting.c.diff?r1=1.124&r2=1.125)
timestamp.c (r1.171 -> r1.172)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/adt/timestamp.c.diff?r1=1.171&r2=1.172)
pgsql/src/include/utils:
datetime.h (r1.63 -> r1.64)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/datetime.h.diff?r1=1.63&r2=1.64)
timestamp.h (r1.66 -> r1.67)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/utils/timestamp.h.diff?r1=1.66&r2=1.67)
pgsql/src/interfaces/ecpg/pgtypeslib:
dt.h (r1.34 -> r1.35)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/dt.h.diff?r1=1.34&r2=1.35)
pgsql/src/test/regress/expected:
timestamp.out (r1.32 -> r1.33)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/timestamp.out.diff?r1=1.32&r2=1.33)
timestamptz.out (r1.22 -> r1.23)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/timestamptz.out.diff?r1=1.22&r2=1.23)
pgsql/src/test/regress/sql:
timestamp.sql (r1.17 -> r1.18)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/timestamp.sql.diff?r1=1.17&r2=1.18)
timestamptz.sql (r1.10 -> r1.11)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/timestamptz.sql.diff?r1=1.10&r2=1.11)