+ Fix ModelToMesh to properly insert mesh data from Tessellation instances
  and to set the model manager on its output collection.
+ Add method to obtain number of corner points for each mesh::CellType.
+ Add methods to add model-entity tags to mesh entities and find
  mesh entities by model-entity UUID.
+ Add a mesh tag named "MODEL" and extend tag/query classes
  to support opaque tags with a subclass to hold UUID data
  as opaque byte-arrays.
+ Add methods to query mesh entities to return their associated model
  entities and to set a model entity (UUID) on all members of a meshset.
  Note that the implementation is a bit hackish because the methods
  provided for working with dense tag values assume all tags are integers.
+ Remove various warnings.