Watching an exit.

@idea from Snake

I thinking today.. A cool idea would be to have the watch command work for an exit as well. I mean it gets annoying and spamy typing look e look e look e look e, over and over again, trying to spot someone. What if you could watch an exit, and if someone walked into the room that you were watching.. it would tell you. It wouldn't like, tell you what people were saying in the other room, just that you spotted someone walking in. And, you could limit watching to one exit. It would be cool for bodyguards looking for trouble, like just watching the door, and nothing else.

I think it would be cool if you could watch an exit, and it would increase your chances of seeing someone sneak in.  Like if you're in a bar and your watching the door.  It could be made so you could only watch one exit at a time.