1. Do not run the prerender in big experiments. Sucks up a CPU for 15
   minutes, just for a jpeg image on the classic interface, that no one
   is looking at.

2. Do not run vtopgen; this takes a long time too, and since we
   immediately run the mapper right after, why bother. A small change to
   mapper will make sure the node counts are set even in alloconly mode,
   since thats the only reason we run vtopgen in the first place.