Apply fixes to off-effort transect filtering

[brandynlucca]

The off-effort transect filter (ingest_nasc.filter_transect_intervals) was not producing the same sized dataframes as expected when comparing to the outputs from EchoPro's remove_unwated_zeros.m. This has now been rectified and tested for all years between 2003 and 2012 (as noted in #404).

[leewujung]

@brandynlucca : I only have a very minor comment above, but I do have a request: Could you can add a schematic that shows the procedure in # Process each unique transect that has filter intervals? Seems like that would be more intuitive (since you already sorted out what Chu's operations were doing). Thanks!

[brandynlucca]

@leewujung:

I only have a very minor comment above, but I do have a request: Could you can add a schematic that shows the procedure in # Process each unique transect that has filter intervals? Seems like that would be more intuitive (since you already sorted out what Chu's operations were doing). Thanks!

Sure! Do you mean a schematic in the documentation (for the implementation?)? Or in the docstring?

[leewujung]

In the documentation.