Implement Minkowski Structure Metric

[Eric Harper]

No description provided.

[Eric Harper]

@jamesaan bump for more information

[James Antonaglia]

I think this was meant to be a reference to this paper, where they describe a method to make neighbor based orientation order parameters less sensitive to the number of neighbors selected for the analysis. Not sure if it's worth implementing, however; might be overkill in most situations. I suspect I had made this an issue as a recommendation as an alternative to a plain Voronoi neighbor method.

[Bradley Dice]

The formula we would like to implement is this one, where A(f) is the surface area of the Voronoi cell facet f, and A is the sum of all facets' areas. This is a nice parameter-free way to do Steinhardt or related order parameters.

To do this, we need:

1. Working neighbor list weights from 3D Voronoi cells. See issue #160.
2. A "weights" argument for the order parameter.

[Bradley Dice]

I am working on this for a project.