Securepy

PyPi release: [SecurePy](https://pypi.org/project/securepy/0.6.0/)

Bugs fixed:
- multiprocessing Process didn't properly join back if it timed out
- StdCapture buffer wasn't reset when an exception occurred.
- Level 3 in Restrictor used `None` for globals rather than empty dict (`{}`)

Features:
- Add Level 0 as regular execution with no builtin limitation
- Add possibility for StdCapture memory limitation to avoid overflow

Finally, [**SecurePy**](https://pypi.org/project/securepy/) is ready for open beta testing. There are certainly a lot of missed issues and problems with it and it's certainly not production-ready but it's now fully usable. It will take time to ensure that the execution of any given code is truly safe, but it's certainly safer than using pure `exec` and it provides you with a lot of configurable options which you can use to adjust the execution to your needs.