vitess-gh/py/cbson

This library implements a simple C bson encoder / decoder for python.
It doesn't support the full bson spec, but supports enough for
our use of it.

The code has no particular dependencies, but at least the encoder has
the following notable caveats:
- It may or may not work on a 64-bit Python.
 (It's possible that it does work, but we've never tried it.)
- It doesn't do a good job of checking for overflows (which could happen
in a few parts, given appropriately malicious input).
- It won't work on a big endian platform.

The python code that uses the bson decoder can work with the pure python
bson decoder, which doesn't have these problems, but is slower.

This code was originally written by Kirk Mcdonald (kgm@google.com) for the
encoder part, and Shalabh Chaturvedi (shalabh@google.com) for the decoder
part.