o Security fixes:
    - Forget all hidden service descriptors cached as a client when
      processing a SIGNAL NEWNYM command.  Fixes bug 3000.  Bugfix on
      0.0.6.
  o Minor bugfixes:
    - Don't allow v0 hidden service authorities to act as clients.
      Required by fix for bug 3000.
  o Code simplifications and refactoring:
    - Allow rend_client_send_introduction to fail without closing the
      AP connection permanently.