Repository diagrams

I just uploaded 9 darcs repository diagrams for the darcs model chapter of the wikibook. I'm not sure these are really useful, that they actually help communicate the idea behind darcs, but it was worth a shot. Just taking a break from all this patch theory stuff, doing something easy for a change. Got a friend at work that seems to get confused by all the darcs commands, so maybe a little visual support could be useful. Or it could just add to the confusion.