Python: use numpy to wrap C++ arrays

[dbrnz]

This should be self obvious. However for some reason Zinc's Python wrappers expose numerical arrays as Python lists, which IMHO is not the best way to do things, so raising this issue...

[agarny]

Yes, we definitely want to make our Python bindings feel "natural" and in this case I agree that this would indeed mean using numpy rather than a Python list.

[agarny]

This has been done. libOpenCOR now has a depedency on numpy since simulation results are now retrieved as NumPy arrays (see PR #576).