[Dune] ALUGrid improvements.

[Robert Kloefkorn]

Hello Dune,

I revised the ALUGrid (3d) implementation. With dune-grid at revision 
5380 the following additional features are now provided:

- intersection iterator for ghost elements, returning the corresponding 
interior element(s)

- father on ghost elements, returns the father element

- hierarchic iterator on ghost elements, returns the ghost children,
only 4 children instead of 8. For data restriction/prolongation this 
cannot be used. Nevertheless it might be useful to have it

- also some bugs concerning the EntityPointer::compactify method have 
been fixed.

As a next step the method operator [] on the Geometry class is removed.

Cheers,

R

-- 

   Robert Klöfkorn           <robertk at mathematik.uni-freiburg.de>

   Mathematisches Institut              Tel: +49 (0) 761 203 5631
   Abt. für Angewandte Mathematik       Fax: +49 (0) 761 203 5632
   Universität Freiburg
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   http://www.mathematik.uni-freiburg.de/IAM/homepages/robertk