  o Minor features:
    - Refactor resolve_my_address() so it returns the method by which we
      decided our public IP address (explicitly configured, resolved from
      explicit hostname, guessed from interfaces, learned by gethostname).
      Now we can provide more helpful log messages when a relay guesses
      its IP address incorrectly (e.g. due to unexpected lines in
      /etc/hosts). Resolves ticket 2267.

