o Major bugfixes:
    - Detect 'ORPort 0' as meaning, uniformly, that we're not running
      as a server. Previously, some of our code would treat the
      presence of any ORPort line as meaning that we should act like a
      server, even though our new listener code would correctly not
      open any ORPorts for ORPort 0. Similar bugs in other Port
      options are also fixed. Fixes bug 6507; bugfix on 0.2.3.3-alpha.

  o Minor features:

    - Detect and reject attempts to specify both 'FooPort' and
      'FooPort 0' in the same configuration domain.  (It's still okay
      to have a FooPort in your configuration file,and use 'FooPort 0'
      on the command line to disable it.) Fixes another case of
      bug6507; bugfix on 0.2.3.3-alpha.