Add needs_facet_normals to custom_integral

[Anders Logg (Chalmers)]

Add function to custom_integral:

bool needs_facet_normals() const;

[Anders Logg (Chalmers)]

I would have wanted to get this earlier but time is short and it's a bad idea to fix issues in the UFC interface at this point. Will fix as part of a larger overhaul for 1.6.

[Anders Logg (Chalmers)]

Marking this as resolved this it will be fixed as part of redesign of measures/integrals for multimesh.

[Martin Sandve Alnæs]

Removing milestone: 1.6 (automated comment)