In Python 2.x an unprefixed string literal produces a byte string.
In Python 3.x an unprefixed string literal produces a textual string.

To produce a byte string in both a b prefix is needed, e.g. b'foo'.
Since I believe Hammer works predominantly with byte strings I have used
b prefixes throughout.

These have no effect in Python 3.x, they are the default. Enabling them
in Python 2.x, enabling them in Python 2.x allows single source
compatiblity.

These are transliterations of the existing C files.
They're not particularly Pythonic or performant, but they're a start.

Example of usage

```
$ echo '  YW55IGNhcm5hbCBwbGVhcw==' | PYTHONPATH=../build/opt/src/bindings/python/ python base64.py
inputsize=27
input=  YW55IGNhcm5hbCBwbGVhcw==
((((89L, 87L, 53L, 53L), (73L, 71L, 78L, 104L), (99L, 109L, 53L, 104L), (98L, 67L, 66L, 119L), (98L, 71L, 86L, 104L)), (99L, 'w', '=', '=')),)
$ echo '  YW55IGNhcm5hbCBwbGVhcw==' | PYTHONPATH=../build/opt/src/bindings/python/ python base64_sem1.py
inputsize=27
input=  YW55IGNhcm5hbCBwbGVhcw==
(97L, 110L, 121L, 32L, 99L, 97L, 114L, 110L, 97L, 108L, 32L, 112L, 108L, 101L, 97L, 115L)
$ echo '  YW55IGNhcm5hbCBwbGVhcw==' | PYTHONPATH=../build/opt/src/bindings/python/ python base64_sem2.py
inputsize=27
input=  YW55IGNhcm5hbCBwbGVhcw==
(97L, 110L, 121L, 32L, 99L, 97L, 114L, 110L, 97L, 108L, 32L, 112L, 108L, 101L, 97L, 115L)
```