make untrusted python code execution safe (pypy-sandbox)

[Stinkfist0]

Migrate to here from realXtend/tundra#87

Python is not very useful now for EC_Script because it is a gaping security hole. It can be made safe by integrating pypy-sandbox, a standalone python interpreter that is run in a sub-process by pypy_interact.py. pypy_interact.py can be run by the current embedded CPython, so we don't need to remove the current embedded python.

Pypy-sandbox by itself is not very helpful because it won't be able to talk to the Tundra API. So we also need ctypes bindings to Tundra that Pypy-sandbox can load. Ctypes is not the only option, if we want to expose only a small subset of the Tundra API, this could be done with pickle messages over a port talking with pypy_interact.py.