Feature/multiprocessing

For faster matrix generation
Same comment as in the very beginning. No need to increase the version number. I will do so once I push it to pypi.

If you *need* the version numbers for internal house-keeping, I would suggest to name them `1.2.0.devX` and simply increment the `X` value. And as this would be in line with [PEP386](http://legacy.python.org/dev/peps/pep-0386/) tools like `pip` should do the Right Thing.