Refactoring the mesh.

src/mesh/initializer/tnlMeshEntityInitializer.h

src/mesh/initializer/tnlMeshEntitySeedKey.h

src/mesh/initializer/tnlMeshInitializer.h

src/mesh/initializer/tnlMeshSubentitySeedCreator.h

src/mesh/initializer/tnlMeshSuperentityStorageInitializer.h

src/mesh/layers/tnlMeshStorageLayer.h

src/mesh/layers/tnlMeshSubentityStorageLayer.h

src/mesh/layers/tnlMeshSuperentityStorageLayer.h

src/mesh/tnlDimensionsTag.h

src/mesh/tnlMeshEntity.h

src/mesh/traits/tnlMeshSubentityTraits.h

src/mesh/traits/tnlMeshSuperentityTraits.h

src/mesh/traits/tnlMeshTraits.h

tests/unit-tests/mesh/tnlMeshEntityTester.h

tests/unit-tests/mesh/tnlMeshTester.h