nents(Topo_type ent_type) doesn't work for mono-topology meshes created with build_box

[cwsmith]

omega_h/src/Omega_h_mesh.cpp

Line 170 in 9621c44

LO Mesh::nents(Topo_type ent_type) const {

Is returning incorrect values for a mesh created with build_box(...). This API was added to support mixed meshes. The original nents(int ent_dim) is compatible with build_box(...).

One option to avoid this is to add a check (compile time?) to see if the mesh is mixed and if not fail in this API.

[cwsmith]

Fixed with the refactor of mixed meshes into its own class: #82