Fixes for REI calculation, docs, and tests

 Changes to be committed:
	modified:   docs/index.rst
	modified:   docs/notebooks/interval_data.ipynb.rst
	modified:   docs/notebooks/receiver_efficiency_index.ipynb.rst
	modified:   py_notebooks/interval_data.ipynb
	modified:   py_notebooks/receiver_efficiency_index.ipynb
	modified:   resonate/filters.py
	modified:   resonate/receiver_efficiency.py
	modified:   tests/assertion_files/nsbs_interval.csv
	modified:   tests/interval_test.py