Changes in version 2017.1.0

UFL 2017.1.0 was released on 2017-05-09.

Summary of changes

• Add the DirectionalSobolevSpace subclass of SobolevSpace. This allows one to use spaces where elements have varying continuity in different spatial directions.
• Add sobolev_space methods for HDiv and HCurl finite elements.
• Add sobolev_space methods for TensorProductElement and EnrichedElement. The smallest shared Sobolev space will be returned for enriched elements. For the tensor product elements, a DirectionalSobolevSpace is returned depending on the order of the spaces associated with the component elements.