Implement simple edge prune

@Elmira88 
Implements the simple delayed edge prune for scaffolding and adds it as another job after the FORWARD job.

Compared to the previous PR, I realized that the tracking needs to be incoming/outgoing, not forward/reverse.  Hopefully you didn't spend too much time there.

The delayed removal *should be* fully compatible with REMOVE_OTHER_INCOMING and REMOVE_OTHER_OUTGOING.