Fix pylint issues

• Fix pylint issues:
  • Allow useless-object-inheritance so we can stay PY2/3 bilingual.
    • This is correctly an unknown option when linting python 2, so we need to whitelist unknown overrides too.
  • Refactor a useless if/return/elif... chain into a sequence of ifs instead.
  • Use chained comparison x <= y <= z instead of x <= y and y <= z.