some changes to tests. now make_infer takes a ripl_thunk which allows for two different backends for the store_obs object and the load_infer unit object. we dont currently test this mix of backends. all tests are passing with puma. we have also allowed example_make_infer to take an observe_range and the tests use the full_observe_range which  is a new method for multinomial model. so we are testing load_observations over multiple years, days and cells and all is passing. problem is that tests are now slow. failing in lite for some weird reason