MAINT: Refactor of domain boundary sides

[jhabriel]

Proposed changes

This PR proposes a refactor of domain_boundary_sides() without changing its functionality. First, the output type was converted from a regular tuple to a namedtuple. This facilitates accessing the boundary sides as attributes (without having to check/remember its position in the returned tuple). The second change is related to the way the boundary sides are picked. Now, the distance between the face-centers and the box sides are computed such that it matches a given tolerance.

P.D.: A cool feature of named tuples is that they also behave as regular tuples. Another cool feature is that they can be transformed into dictionaries.

Types of changes

What types of changes does this PR introduce to PorePy?
Put an x in the boxes that apply

• Minor change (e.g., dependency bumps, broken links, etc).
• Bugfix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• Testing (contribution related to testing of existing or new functionality).
• Documentation (contribution related to adding, improving, or fixing documentation).
• Maintenance (e.g., improve logic and performance, remove obsolete code, etc).
• Other:

Checklist

Put an x in the boxes that apply or explain briefly why the box is not relevant.

• The documentation is up-to-date.
• Static typing is included in the update.
• This PR does not duplicated existing functionality.
• The update is covered by the test suite (including tests added in the PR).

[IvarStefansson]

Nice! Wouldn't a named tuple be a much better solution for bounding boxes as well?

[jhabriel]

Yes. That was my immediate thought as well. Should I create an issue for that?

[IvarStefansson]

Yes. That was my immediate thought as well. Should I create an issue for that?

Yes, please. Or, if you have the time, have a look and just implement it if it's relatively easy (if overhead of creating issue is substantial relative to overall effort).