dmarek-flex

Looks good, but I think I will wait to approve until I try it with the backend changes.

> > We may need some validations to avoid confusion when people don't order their structures correctly? > > You are right, currently 2D PEC has the same issue. The...

I have been looking into this issue. At the moment I experience two problems using the backend solver. - If discretization is improper, the PEC is missed completely and no...

@tylerflex @caseyflex I think this issue was addressed in this [PR](https://github.com/flexcompute/tidy3d/pull/1395). It is possible to treat it more elegantly, but I think the fundamental issue was addressed.

Ok this PR is ready for review now! A couple of things that I was not confident about: - I had to use this "noqa" commands to get rid of...

> This is tons of work! First pass except for custom path integral part. All look solid and easy to follow. One question when you compute the current by using...

> @dmarek-flex looks good to me, barring a few changes to get the tests working, I think this should be basically good to go? Yep, think I just need to...

> looks like it just needs submodule update? Yea, but I am also trying to diagnose a regression on the backend tests that I just noticed before merging. Ok fixed,...

I had a working branch with some basic support, but it ended up looking like a not so trivial implementation to handle all cases and not a high priority item.

I worked on reproducing this and testing how discretization affects the results. Discretization has no effect on the field distribution, so I believe the issue is due to the simple...