Update /whois

- Removed broadcasting remnants
- Show if a user is offline
- Show private rooms when used by an admin or oneself and ranks in current rooms
- Use room titles for chat rooms
The reason I don't like displaying private rooms in `/whois` is the same reason I don't like displaying alts in whois – unless the user is misbehaving and the mod/admin sees a need to look at these things, there's no great need to infringe on the user's privacy in those ways.

Maybe we should split the investigative stuff into separate commands.