Add Option to Imprint the Assembly Before Meshing

[jmwright]

The problem is that the mesh between two contact faces is not conformal.

Surfaces in contact need to be conformally meshed, which means we need imprinting. This plugin needs to offer the option to imprint the assembly before returning the tagged gmsh object.

[adam-urbanczyk]

Imprinting is already implemented in CQ, why would you add it here too?

[jmwright]

@adam-urbanczyk The intention is to use CQ's imprinting in this plugin, not re-implement it. I don't know what form exactly that will take yet.

[jmwright]

Finished in #20