MeshAlignmentOneToMany
This is a base class for MeshAlignment1D3D and MeshAlignment2D3D. It builds a mapping between elements/faces for one of the following cases:
1D-to-3D: A 1D subdomain and a 3D boundary
2D-to-3D: A 2D boundary and a 3D boundary
Each element on the primary side maps to multiple elements on the secondary side.