Enhance shaper so it can use C2C assembly.

[BradWhitlock]

I read through the C2C docs and it supports making assemblies of multiple contours. Since I was making a new dataset for Klee, I tried grouping some contours into assemblies since it could make the YAML input file smaller by making a material per assembly. Axom complained at runtime.

[WARNING]: Input was an assembly! This is not currently supported
[WARNING]: reading C2C file failed, setting mesh to NULL

If things need to be handled one contour at a time, perhaps if we encounter an assembly we can return a vector of contours and associate them all with the material that caused the assembly to be loaded. This would be nicer than having to write a large YAML input file.

• Support C2C assemblies in Klee

[kennyweiss]

Bump.

An axom user mentioned that it would be helpful to have assembly support.