Allow lazy multipliers

[qntm]

For #107.

• Couldn't get the custom Pylint extension to load, so scrapped it.
• Couldn't figure out why this utterly bizarre custom Pylint init-hook wasn't working locally, so scrapped it.
• Seems like despite constraints.txt, new versions of all of these packages have changed the way Pylint works, so scrapped the constraints file.
• Some Pylint extensions seem to now be core rules, so altered the configuration accordingly.
• Fixed some linting issues. Notably, added setuptools to requirements.dev.txt.
• Added unit tests for lazy quantifiers and updated the parser to make the tests pass.
• Documentation.