Release history and non-trivial changes:

PySkein 0.6.1 (2010-06-07)
--------------------------
    - Fixed a bug in copy()ing tree hash objects

    - Made hash objects picklable

    - Improved repr() of hash objects

    - Fixed several issues with Python 3.0


PySkein 0.6 (2010-05-14)
------------------------
    - Incremental tree hashing with arbitrary tree parameters

    - Restricted digest_bits to < 2^31 bits (256 MB!)

    - Disabled precomputed IVs (their performance benefit is negligible)

    - Deprecated all non-keyword arguments of skein*() functions
      except 'init' and 'digest_bits'


PySkein 0.5.2 (2010-03-25)
--------------------------
    - Release the GIL to allow multiple threads to hash in parallel
      on multi-core systems


PySkein 0.5.1 (2010-02-18)
--------------------------
    - Fixed reference leak when changing tweak value on threefish object


PySkein 0.5 (2009-09-25)
------------------------
    - Updated rotation constants to new Skein specification (version 1.2)

    - Added implementation of Skein PRNG


PySkein 0.4 (2009-08-23)
------------------------
    - Hashing with personalization string

    - Hashing with nonce value


PySkein 0.3.1 (2009-08-13)
--------------------------
    - Improved demo script "threefish"

    - Better compatibility with Python 3.1


PySkein 0.3 (2009-01-05)
------------------------
    - Threefish block decryption

    - Demo scripts "skeinsum" and "threefish"


PySkein 0.2 (2008-12-04)
------------------------
    - Support for message authentication codes

    - Threefish block encryption (but no decryption)

    - Fixed one or two reference leaks


PySkein 0.1 (2008-11-22)
------------------------
    - Skein-256, Skein-512, and Skein-1024 hashing
