[kronolith] bug in categories

[Kurt Van Schaeybroeck]

I found what's going wrong, but this still needs
to be solved.

Imagine : admin with 6 categories :
0 Personal 1 First 2 Second 3 Third
4 Business 5 Pleasure 6 Personal

an other user who uses a shared cal of the admin,
has only 3 categories :
0 Business 1 Pleasure 2 Personal

When the admin sets an event with cat. Business,
the database gets "4".

When the user views the events, it's seems that kronolith
takes the value of the db "4" and tries to link it
to the array of event_colors from the user.
But, Business isn't index 4 there, so the wrong color
is displayed!

Hopefully this can get some people started in the right way.

Kurt