/slowlockdown command

Like /lockdown, but doesn't tell existing battles to hurry up.

For use in smogtours, but I guess other servers can use it too.
Show error message when joining active battles
Room refactor

Now ChatRooms and BattleRooms inherit from a generic Room prototype,
which means, among other things, less code duplication between them.

In the process, sending old message times has been refactored to be
much more sane, and now uses |c:| and |:| instead of |tc|.

Other changes include that user symbols now show up in battles,
like in chat rooms.
Drop support for /help all

Also drop support for the rank-specific command lists, like /help @