A more convenient convenience method to create a sampler!

[lbluque]

Is your feature request related to a problem? Please describe.
Please describe the problem you are trying to solve.
Not related to a problem, but I find myself creating to many ensembles that I rarely use directly.
Except for obtaining an initial occupancy, but other than that not really used for anything else.

Describe the solution you'd like
Please describe the desired behavior.
Perhaps having a convenience constructor in the sampler to create directly from a Cluster Expansion like so,
Sampler.from_cluster_expansion(expansion, supercell_matrix, ...all other goodies needed)

Describe alternatives you've considered
Please describe alternative solutions or features you have considered.
Doing so would likely limit how much tweaking a user could do for each of the classes involved (processor, ensemble, kernel, etc) but for those cases one can just fall back to the lengthier more verbose construction of each class individually.

[lbluque]

I'm not sure how much easier this makes using the code.....

labeling as wontfix for now. In case anyone actually wants it, feel free to bump this.