Major change: CTransaction, CBlock, etc. now come in immutable (default) and mutable forms. In most cases mutable and immutable can be used interchangeably; when that is not possible methods are provided to create new (im)mutable objects from (im)mutable ones efficiently.

Other changes:

• New BIP70 payment protocol example. (Derren Desouza)
• Rework of message serialization. Note that this may not represent the final form of P2P support, which is still in flux. (Florian Schmaus)
• Various bugfixes

Finally starting this release, git tags will be of the form 'python-bitcoinlib-(version)', replacing the less specific '(version)' form previously used.