Cleaned up parameterized tests.

File names are now these:

    abjad$ ls -1 tools/test

    test___copy__.py
    test___doc__.py (*)
    test___init__.py
    test___repr__.py
    test_pickle.py
    test_signatures.py
    test_storage_format.py

Activated test___copy__.py.

Only test___doc__.py remains to be activated; all other parameterized tests are
now activated and running against the system as part of the complete pytest
battery.

More docstrings will have to be written to activate (and pass) test___doc__.py.