Volume Mesh Support for Prism and Pyramid Cell Types. Fixes #337

[mgsutton]

This PR tries to address this issue: #337

[mgsutton]

@nmwsharp, please take a look at this when you have a chance and let me know what you think. For a simple test mesh comprising of a hex, two prisms, a pyramid and a tet, it produces results that look like this.

I've tried to update the docs here, at least for cpp: nmwsharp/polyscope-docs#18

[grindstm]

I am highly interested in this feature. Is further contribution needed?

[mgsutton]

Just waiting on review/feedback.

[nmwsharp]

Hi, thanks for this and pardon the slow response, looking into it a bit now.

One immediate question: I see that computeConnectivityData() now has a keyed set detecting "real" edges, but it's not clear to me why this is necessary.

[nmwsharp]

(fyi I may just push directly to this branch to resolve things and get it merged if I see obvious solutions to small problems)

[nmwsharp]

Merged! Note that I changed the indexing on the prism type from your version, because I felt it was inconsistent with the others. (The others all had a "bottom" face that is clockwise-inward wound).

Let me know if anything doesn't seem right. Thanks for this!