depreciate sectionheaders.py

[aerispaha]

Replace with JSON or YAML file with more flexibility and information about each INP section (e.g. column header variation, units)

[dickinsonre]

Sounds good, do you have an example JSON or YAML file?

[aerispaha]

@dickinsonre, I've started using this JSON file. Structure is very TBD right now, but the goal is maintain a central location where section heaeders, column names, and meta data can be stored and used as the foundation for much of the functionality in swmmio.

I suppose this could be stored still within a python dictionary object, but it seems to make more sense to store text configuration and meta data in a non-Python file.