mu-FD-simulation

mutation testing techniques comparison w.r.t. fault detection.

method call for mbert and Pit-hom: fd.Simulation.process_x_mutants_by_ranked_pool_by_random_pools > PractitionerXByPoolPoolByPool

method call for the others: fd.Simulation.process_x_mutants_by_random_pool

next todos:

• add a running example.
• testing.
• documentation.