Implementing superentity initializer.

TODO

src/mesh/config/tnlMeshConfigBase.h

src/mesh/layers/tnlMeshStorageLayer.h

src/mesh/layers/tnlMeshSuperentityAccess.h

src/mesh/layers/tnlMeshSuperentityStorageLayer.h

src/mesh/tnlMesh.h

src/mesh/tnlMeshEntity.h

src/mesh/tnlMeshEntityInitializer.h

src/mesh/tnlMeshInitializer.h

src/mesh/tnlMeshSuperentityInitializerLayer.h

src/mesh/traits/tnlMeshConfigTraits.h

src/mesh/traits/tnlMeshSuperentitiesTraits.h

tests/unit-tests/mesh/tnlMeshEntityTester.h