Shadow Rift modification

- No portals in rented rooms. This fixes a bug that allowed players to
raid private rooms and loot chests. Also, rented rooms are the only
private areas in the entire game, lending special abuse to portals made
there.

This is just an initial step. I think it's clear Shadow Rift need some sort
of fundamental change. Right now they're just a ridiculous and abusive
economic advantage.

I'll have something up to modify Shadow Rift soon. Probably ditching
the prism aspect, because non-pvp prism spells are really just a layer of
mule abuse requirement. If this spell is going to exist at all, it should
be pvp-related, available to everyone, and fun.