Revisit ragged array writing and reading

[dblodgett-usgs]

The function we have is tested atleast, but it needs to be revisited in light of other work on the package.

1. Use package env vars instead of hard coded strings.
2. Update inputs and documentation to be parallel with other functions.
3. Write needed functionality in checker function to get all the details out of a file.
4. Create a reader function.