Improved the tolerance handling in the auditor script

This is a re-push of !116 (closed) containing original commit by @jmwright

Adding as a new MR because the branch settings on !116 (closed) do not allow pushing to contributor branch and therefore cannot be rebased automatically.

Original description:

Previous method of allowing small variations between current KiCAD STEP models and the newly generated models was not very clean and failed in some edge cases (in the case of a -0.001 difference). This version is cleaned up and still limits the number of decimal points displayed to a user.