Major changes between releases:

0.5
    - Updated rotation constants to new Skein specification (version 1.2)
    - Added implementation of Skein PRNG

0.4
    - Hashing with personalization string
    - Hashing with nonce value

0.3.1
    - Improved demo script "threefish"
    - Better compatibility with Python 3.1

0.3
    - Threefish block decryption
    - Demo scripts "skeinsum" and "threefish"

0.2
    - Support for message authentication codes
    - Threefish block encryption (but no decryption)
    - Fixed one or two reference leaks

0.1
    - Skein-256, Skein-512, and Skein-1024 hashing
