More Python Machines

Created by: gcarleo

This PR ports the all-things pure-state RBMs to python

• RbmSpin
• RbmSpinSymm
• RbmSpinReal
• RbmSpinPhase
• RbmMultiVal
• Jastrow
• JastrowSymm

Important change is that most things are implemented in a single class, instead of doing multiple classes as in the old c++ code. For example, RbmSpinReal is just a short-cut for

RbmSpin(...,dtype=float) 

In turn this means that we have some functionalities that weren't available before, for example we can have real-valued RbmMultiVal just changing dtype in its constructor.

Symmetries in the RBM yet are implemented with a simple logic, i.e. RbmSpinSymm, is just a short-cut for

RbmSpin(...,symmetry=True)

Notice that now we can pass an arbitrary automorphism vector to symmetry (instead of just passing True, so that a graph is not explicitly required in the incoming hilbert space).

This immediately allows new machines that weren't available before. Most notably, we now have a nice RbmMultiVal with symmetries, that is pretty handy/very accurate for the translation-invariant Bose Hubbard model. I have update the example in BoseHubbard1d/bosehubbard1d.py accordingly. @VolodyaCO this might be of interest for you if you are still working on the Bose Hubbard (also see #328 (closed).