Update the join_bitmasks and tests

src/main/python/Octeres/bitmask/bitmask.py

src/main/python/Octeres/bitmask/bitmask_graph_search.py

src/main/python/Octeres/bitmask/bitmask_lite.py

src/main/python/Octeres/data_generation.py

src/main/python/Octeres/scripts/performance_run.py

src/test/python/test_random_generation.py