Quiz

Just to jump in here... I did some work on this a while back (and it's probably why some of this code is so weird) because some people where using huge numbers of categories - we tested with 800 IIRC. With those numbers it used to failed completely. I rewrote the sort routines to make them more complicated but with a much better (number of swaps per category). I'm not sure it's related in this case but if it is any big changes should really check that they do not re-introduce any such problems.