[Dune] EntityPointer finished

[Christian Engwer]

> I have one question left. Due to the Constructor protected change
> yesterday in the Geometry class, AlbertaGrid compiles not with the
> protected Constructor. The error ocures, when the BoudanryEntity class
> is instanciated. I dont know why. How did you solve that prob for SGrid?

As the BoundaryEntity is broken I just skipped the broken part.

I guess this will work after you implement a copy constructor for
SIntersectionIterator and SBoundaryEntity.

I will chack this...

Cheers Christian