Patent-client

- Add support for document downloads from the USPTO PEDS interface
- Fix flakey tests
- Update dependencies

- Merge pull request ensuring that INPADOC produces consistent typing (PR 37)
- Update dev dependencies in Pipfile

- Added foreign priority support back to PEDS API
- Revised and simplified documentation to match v.2, including using Sphinx Autodoc
- Added doctest support to documentation to confirm examples still work
- Added docstrings throughout
- Labeled some broken things as broken

- Fixed problem where Inpadoc was indexing improperly

- Major update with breaking API changes
- Refactored all API's to use requests_cache rather than custom caching scheme
- Uses Marshmallow for data validation, and memory-efficient dataclasses for all objects
- As part of the above, all API's now re-use the same requests.Session() object
- Deleted a ton of unnecessary code (Deleted code == debugged code)
- NOTE: Documentation not yet up-to-date. That is the next project

- Renewed commitment to adhere to semantic versioning
- Added several new synthetic data attributes, including expiration date calculations
- General updates and improvements, including an overhaul of the base Manager and Model classes