Add the pytest ini

[jameshalgren]

Updated the layout to follow this common model and included the pytest.ini file in the right location. Running pytest and python -m pytest from any position within the repository should be successful.

.
├── LICENSE.txt
├── nwmurl
│  ├── __init__.py
│  └── urlgennwm.py
├── pytest.ini
├── README.md
├── setup.py
└── test
   └── test_cases.py

Also, reformatted a number of files according to strict formatting rules, so there are a few changes in other source files not related to testing.

Many complicated but useful discussions here:
https://stackoverflow.com/questions/41748464/pytest-cannot-import-module-while-python-can

And a very good example here:
https://github.com/Mrodent/pytest_probs/blob/main/src/core/bubble.py

We boiled things down to the minimum.

[RohanSunkarapalli]

Looks useful and seems working anywhere when you run "pytest". Will modify the changes to the format and push the changes.