Done ISO 8601 intvars and functions, again

[K_Meinhard]

Rex,

Lucho has now written a full implementation of ISO 8601 intvars and
functions for 4DOS. I'd still like to see them implemented in TCC too,
as they are essential for European users. They include

_ISODOWI Numeric day of the week (Mon = 1, etc., Sun = 7)
_ISOWDATE Current ISO 8601 week date (yyyy-Www-d)
_ISOWEEK Week of the year pursuant to ISO 8601
_ISOWYEAR Current ISO 8601 week date year

@ISODOWI[date] Numeric day of the week (Mon = 1,
etc., Sun = 7)
@ISOWEEK[date] Week of the year pursuant to ISO 8601
@ISOWYEAR[date] ISO 8601 week date year
@DATECONV[date[,format]] Convert date from one format to another

and a fifth parameter to @AGEDATE und @MAKEDATE for the ISO weekdate
format (yyyy-Www-d) as well as the ability to understand this format in
all other date-related functiuons and the DATE command.

Mit freundlichem Gruß,

Klaus Meinhard