Idiomatic Python bindings for Google Go

Instead of simply duplicating the Python C API in Go, this is an attempt to provide the Python API in a form that fits with writing normal Go code.

This means that PyFoo_XXX(foo, ...) is foo.XXX(...), and PyFoo_Check(obj) is foo, ok := obj.(*Foo) to give a couple of examples.

Currently, only Python 2.7 is supported. Though I do hope to add support for other versions in the future.

Note: Python 2.6 support is currently available on the python2.6 branch.