  o Minor bugfixes (initialization):
    - Initialize the subsystems in our code in an order more closely
      corresponding to their dependencies, so that every system is
      initialized before the ones that (theoretically) depend on it.
      Fixes bug 33316; bugfix on 0.4.0.1-alpha.

  o Minor features (tests):
    - Initialize all subsystems at the beginning of our unit test harness,
      to avoid crashes due to uninitialized subsystems.
      Follow-up from ticket 33316.

  o Code simplification and refactoring:
    - Merge the orconn and ocirc events into the "core" subsystem, which
      manages or connections and origin circuits.  Previously they
      were isolated in subsystems of their own.
