added TensorGrid to init

tfields/__init__.py

@@ -13,6 +13,7 @@ from tfields.mask import evalf
 
 # classes:
 from tfields.core import Tensors, TensorFields, TensorMaps, Container, Maps
+from tfields.tensor_grid import TensorGrid
 from tfields.points_3d import Points3D
 from tfields.mesh_3d import Mesh3D
 from tfields.triangles_3d import Triangles3D