Renaming dataclasses folder, fixing linting.

[astronomerritt]

I did an incredibly silly thing when I named one of the Adler folders "dataclasses" - that's the name of an inbuilt Python library. (Which I am actually USING so you think I'd know.) We've gotten away with it up until today - but now I'm getting circular import errors on adler-day.

I've renamed the "dataclasses" folder to "objectdata" and carried the change through to everywhere in the code and in the notebooks.

I also fixed linting, yay!

Review Checklist for Source Code Changes

• Does pip install still work?
• Have you written a unit test for any new functions?
• Do all the units tests run successfully?
• Does adler run successfully on a test set of input files/databases?
• Have you used black on the files you have updated to confirm python programming style guide enforcement?

[jrob93]

Looks good. I've fixed the notebook in docs and checks look to be passing now.