Changelog for bencoding-0.4.0.0

0.1.0.0: Initial version.
0.2.0.0: Added default decoders/encoders using GHC Generics.
0.2.2.0: Arbitrary length integers. (by specification)
0.3.0.0: Rename BEncode to BValue and BEncodable to BEncode.
0.4.0.0: Faster dictionary conversion.