Refactoring (change the module name "model_checker" to "verifier")

env/env_base.py

env/simple_intersection/simple_intersection_env.py

env/simple_intersection/vehicles.py

options/simple_intersection/maneuvers.py

options/simple_intersection/mcts_maneuvers.py

verifier/LTL_property_base.py

verifier/__init__.py

verifier/atomic_propositions_base.py

verifier/parser.py

verifier/scanner.py

verifier/simple_intersection/AP_dict.py

verifier/simple_intersection/LTL_test.py

verifier/simple_intersection/__init__.py

verifier/simple_intersection/classes.py