Convert bench_cffi_access.py to use unittest and helper.py
flake8 Tests/make_hash.py
Convert large_memory_test.py to use unittest (and change second XDIM on line 30 to YDIM)
Convert large_memory_numpy_test.py to use unittest (and change second XDIM on line 36 to YDIM)
Remove last dependencies on tester.py and remove file