o Minor bugfixes:
    - On SIGHUP, do not clear out all TrackHostExits mappings, client DNS
      cache entries, and virtual address mappings: that's what NEWNYM is
      for.  Bugfix on Tor 0.1.0.1-rc; fixes bug 1345.
    - When TrackHostExits is changed from a controller, remove any
      mappings for hosts that should no longer have their exits tracked.
      Bugfix on Tor 0.1.0.1-rc.