Read additional information for DAGMC cells from openmc.lib

[pshriwise]

…penmc.lib

Description

This PR adds temperature reading (no overrides... yet) to DAGMC universes and bounding box information from openmc.lib. The latter may be useful for efficient sampling of volumetric sources over a given cell.

As described in #3398, it also

• sets DAGMCCell IDs as int instead of np.int32 for consistency.
• changes DAGMCCell.bounding_box from a method to a property.

Fixes #3398

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[pshriwise]

On second thought, I don't think populating the DAGMCCell's with bounding boxes is such a good ideal. I'd forgotten that the bounding boxes coming from the DAGMC C++ API are really oriented boxes at the top of the BVH that have been re-oriented to be axis-aligned and, while valid, it makes them extremely conservative/very loosely fitting.

[shimwell]

Perhaps this reads better than using the \

Suggested change

	warnings.warn('Changes to temperatures on DAGMCCell\'s will not be reflected in transport')
	warnings.warn("Changes to temperatures on DAGMCCell's will not be reflected in transport")

[shimwell]

On second thought, I don't think populating the DAGMCCell's with bounding boxes is such a good ideal. I'd forgotten that the bounding boxes coming from the DAGMC C++ API are really oriented boxes at the top of the BVH that have been re-oriented to be axis-aligned and, while valid, it makes them extremely conservative/very loosely fitting.

Is this PR something we want to go ahead with

Should we remove the ability to read the DAGMC bounding box but keep these two parts of the PR

• sets DAGMCCell IDs as int instead of np.int32 for consistency.
• changes DAGMCCell.bounding_box from a method to a property.