In an October 2014 discussion <https://sourceforge.net/p/open-cobol/discussion/lounge/thread/2c5dac3f>,
it was decided that there needed to be more open-source COBOL code.

So, to improve the situation, here is a small program, get-iso-week, that
calculates the week of the year.

It comes in two versions:
  * a more modern version that splits it into a few functions
  * a COBOL-85 version (compiling successfully in Fujitsu COBOL85)

The program is a translation of get_iso_week() from the FORMATTED-DATE patch
<https://sourceforge.net/p/open-cobol/patches/19/> and is licensed under the GPL
v3.

Example usage:

MOVE FUNCTION INTEGER-OF-DATE (20120101) TO day-num
CALL "get-iso-week" USING day-num, year, week
DISPLAY "2012-01-01 is in week " week " of " year
*> Displays "2012-01-01 is in week 52 of 2011".
