  o Minor bugfixes (security usability):
    - Elevate the severity of the warning message when setting
      EntryNodes but disabling UseGuardNodes to an error. The outcome
      of letting Tor procede with those options enabled (which causes
      EntryNodes to get ignored) is sufficiently different from what
      was expected that it's best to just refuse to proceed. Fixes bug
      8180; bugfix on 0.2.3.11-alpha.
