[dune-pdelab] dune-pdelab | Feature: Divergence and curl as DGF (#15)

[Christian Engwer]

> (And I do think that curl and divergence GridFunctions are important enough to
> have around.)

it is not only div and curl. There are the new adapters that Adrian
proposed and we are not talking about the old implementations, which I
want to keep, if now good reason speaks against it.

Christian