Implement Hybrid Monte-Carlo

[Luthaf]

This is easy: just use the functionalities around to build the hybrid move

[Luthaf]

See http://www.sciencedirect.com/science/article/pii/037026938791197X for the paper describing this method.

[Luthaf]

A question popping into my mind would be: what happens when NVE is performed and temperature drops considerably?

@g-bauer in #51 (comment)

I do not remember, but I have seen this. I'll check my notes tomorrow. I think that this is why you will want to use NVT simulation instead of NVE with the same temperature as the MC simulation. If/when the MD simulation is at equilibrium, the actual potential energy should only fluctuate around the MC energy.