2002-01-10  Jon K Hellan  <hellan@acm.org>

	* src/functions/fn-date.c (gnumeric_isoweeknum): New
	function. Return the ISO 8601 week number of date.
	(gnumeric_weeknum): New function. Return week number of date
	according to method.  (date_functions_init): Include them in
	table.

	* src/datetime.c (datetime_isoweeknum): Added. Return the ISO 8601
	week number of date.
	(datetime_weeknum): Added. Return week number of date according to
	method.

	* src/datetime.h: define week numbering methods. Declare
	datetime_isoweeknum and datetime_weeknum.