DEP: Warned about future removal of raw score methods attached to the atoms object

Added warnings when using the methods being added to the atoms object in ase.ga. That is the get and set methods for raw_score, parametrization and neighbor_list. Now there is regular functions in ase.ga.init (imported by e.g. from ase.ga import get_raw_score) that takes an atoms object as an argument and does the same as the old functions.