Removing duplicate triangles

[shimwell]

I originally wrote this issue up over on another repo
fusion-energy/brep_to_h5m#27

But I think it should live here instead

Basically, we have surfaces from different volumes that touch, in this case we have two sets of triangles that are duplicates. We should be able to remove one set and still have dagmc compatible geometry by flipping setting the surface sense

This might mean refactoring the input arguments from triangles and vertices to triangles broken down into faces and vertices

Then duplicate faces could be found.

Brep-to-h5m probably needs to have the option of outputting the mesh as triangles in each solid broken down into faces