[Dune] IntersectionIterator changes finished.

[Christian Engwer]

Hi,

> the change of the IntersectionIterator interface is finished.
> All old methods are marked as deprecated.
> Also the Dune code should compile again, at least the grid checks do.

How should be neighbor methods be used now? I guess it is neighbor()
and the old methods leafneighbor() and levelneighbor() are to be
removed.

One question striked me though. I would expect leaf- and
levelitersectioniterator to be of a different type, because they
implement a different semantic. How must I adjust the classes? (I
wanted to update yaspgrid and sgrid)

Thanks
  Christian