[dune-fem] Bug in jacobianAll

[Agnese, Marco]

Ok I found the issue.
In my code I was creating the local matrix calling 

op.localMatrix(*entityIterator,*entityIterator); 

With the copyable entities is not allowed any more. The solution is to do

const Entity& entity(*entityIterator);
op.localMatrix(entity,entity);

Cheers,
Marco.