RFC: static sanity checks for energy models
Created by: Elieva
@derkling, @credp, @qperret, @valschneider Please, can you have a look to check if it covers all the tests that you had in mind for the sanity check of the energy model? and if the global form of the tests is fine for you (that the tests are executed in preliminary.py and test_energy_model.py etc...) or if you have other suggestions?