RE: fdo 50950 make (ISO)WEEKNUM comply with ODFF1.2, advise asked

Hi Eike,

> Please see my splinter review in
> https://bugs.freedesktop.org/show_bug.cgi?id=50950#c6

All your comments have been processed in the code (I learned some new things too, thank you !).
It now works fine for all possible argument values, including levibng out the optional value for 
WEEKNUM and illegal arguments.

Now I will start on seeing how old-style documents are interpreted and how I can handle that as 
'smooth' as possible (unnoticeable for user, I mean).

(It may be after my holidays before you hear from again)

Winfried