ISO weeknumbers

[larjo solifer ee tut fi]

	Hello gnomecal people,

I decided to take a shoot at gnome development because I definitely need a
calendar that can display ISO weeknumbers. They are being used quite
frequently in our university scheduling, I believe this is quite common
in Europe. Korganizer does support them, and there is a plugin to ical
as well.

I'm looking for help now. I have done the following:

- updated prop.c to display and set the option. It is a check button that is 
  active only when weeks start on Monday (ISO specified) and added the 
  corresponding extern to main.h and main.c

  The checkbutton is not currently on right place and I need to rewrite
  the box building functions in prop.c to implement this correctly.

- written a weeknumber evaluation stub in timeutils.c, the implementation 
  of the algorithm is quite straightforward.

- added weeknumber evaluation and display on week view

The next task will be rewriting gnome-month-item to include weeknumber column
if the option is selected. As this is implemented as a canvas item, I thought
that it would be simple enough to follow Federico's model with the item
groups.

It is not. I'm currently at loss because the canvas does not behave as I 
expected. I have been able to make room for the weeknumber column, but when
I create the canvas items for the new column, they either segfault at will or
at best do not update correctly. I have checked every call to canvas item
manipulation and I believe I pass only valid parameters and pointers. 
Apparently I'm overlooking something in canvas operation, or there is some 
stupid bug lurking out there.

Any hints at debugging will be appreciated. I'm using ddd at the moment, which
is ugly and slow buggy and _slow_. It bleeds memory like hell.

	Regards,

	Jussi

-- 
  Jussi Larjo , Tampere University of Technology, Finland = larjo@cc.tut.fi
	"And I'm not frightened of dying. Anytime will do, I don't mind.
	Why should I be frightened of dying? I see no reason for it.
	You gotta go sometime."  -Roger "The Hat".