I had to make a slight diddle to work with Python 1.4, which
we and some of our customers are still using. :(

I've also made a few minor enhancements:

  - You can now both get and set the memo using a 'memo'
    attribute.  This is handy for certain advanced applications
    that we have.

  - Added a 'binary' attribute to get and set the binary
    mode for a pickler.

  - Added a somewhat experimental 'fast' attribute.  When this
    is set, objects are not placed in the memo during pickling.
    This should lead to faster pickling and smaller pickles in
    cases where:

      o you *know* there are no circular references, and

      o either you've:

        - preloaded the memo with class information
          by pickling classes in non-fast mode or by
          manipilating the memo directly, or

        - aren't pickling instances.