Re-add left and top priors for nonzeros which were accidentally commented out in October. Brings walk to 6907692 down from 7002815 compared to the original size 8021233.
Re-add left and top priors for nonzeros which were accidentally commented out in October. Brings walk to 6907692 down from 7002815 compared to the original size 8021233.

danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264,danielrh/losslessh264