Res scat

This is a continuation of PR #232 which adds a capability for more accurately modeling resonance scattering events.  Documentation of the methods and required input has been added, as has a simple test case.
You should put a try, finally block around the test calls and teardown, i.e.:
```python
try:
    test_run()
    test_created_statepoint()
    test_results()
finally:
    teardown()