tor/changes/forget-rend-descs-on-newnym

  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 Major bugfixes:
    - When we find that we have extended a hidden service's introduction
      circuit to a relay which isn't listed as an introduction point in
      the HS descriptor we currently have for the service, we now retry
      one of the introduction points in the current HS descriptor.
      Previously we would just give up.  Bugfix on 0.2.0.10-alpha; fixes
      bugs 1024 and 1930.
  o Minor bugfixes:
    - Don't allow v0 hidden service authorities to act as clients.
      Required by fix for bug 3000.
    - Ignore SIGNAL NEWNYM commands on relay-only Tor instances.
      Required by fix for bug 3000.
  o Code simplifications and refactoring:
    - Allow rend_client_send_introduction to fail without closing the
      AP connection permanently.