Handle bad WILL_ROOMS configuration a little better

If you messed up your `WILL_ROOMS` configuration, Will would die. This changes it so Will still goes online and just ignores the bad room, and logs the available rooms that you probably should have been using in the first place. Now Will will still get online and work for private messages but not in rooms.

I don't know what the output would look like for someone with a lot of available rooms.

TODO

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