Introduce concept of protection levels for anti-abuse defense.

These can be manually configured (though they are off by default),
to protect the game server network from abuse.  Successively more
severe protection schemes apply to non-member players when
activated:

* Quarantined always on login,
* Quarantined and can only send tells to DMs (and nothing else).
* Quarantined and booted in 5 seconds with short message.
* Quarantined and immediately booted.