allow vengeance against nymphs except for specific case

allow vengeance against nymphs except for specific case

From: "Ken Arromdee" :
> My point is that you should be allowed to take vengeance on thieving
> nymphs too.  The reasoning "a real knight wouldn't kill a nymph for stealing"
> doesn't make sense because the things a real knight would do instead (like
> arresting) aren't part of the game.

This is a compromise.  This doesn't allow vengeance when you were
told "you gladly hand over ...", but does for most other cases, and for
leprechauns.