Adding EMCF solver

[piyushrpt]

• Unwrapping in time first and then in space
• Support for computing residues and flood filling using gradients
• Support for including models when computing residues
• Example usage can be found in tests/workflows/test_emcf.py

[mattcalef]

This looks good. I've added a few non-blocking issues, which we can tackle later.

[piyushrpt]

I will leave this branch till @gmgunter gets a chance to take a better look. No rush. The feature branch should be fully functional.

[gmgunter]

Thanks for your patience! I'm starting to catch back up now

[piyushrpt]

I think the comments here have come in a little too late to address them satisfactorily and not impact the two other PRs that are queued up. I can included them in the last of the PRs that are stringed together. Does that work?

[gmgunter]

Does that work?

Yeah, that's totally fine with me. I'll continue adding comments as I read through the changes, but they can be addressed in subsequent PRs. I'll approve each of the backlog PRs once I'm finished reviewing it, even if there are remaining comments, until I'm caught back up with you.

[gmgunter]

Thanks, LGTM, let's go ahead and merge this one. I appreciate it if you could address the comments below in a subsequent PR (or respond to them if they're off-base).