[Dune] EntityPointer constructor from Entity and method compactify.

[Robert Kloefkorn]

Hello Dune,

as promised in Berlin I implemented a way to construct entity pointers 
from entities. Given an entity one can construct an entity pointer by 
calling

EntityPointer p ( entity );

Furthermore, the entity pointer now has a method named 'compactity()'
which releases all temporarily used memory of the entity pointer in 
order to keep memory allocation small for a list of entity pointers.

Although the method is implemented for all Grids in dune-grid
this feature is at the moment only supported by ALUGrid and SGrid.
All other implementations contain an empty method.

Regards,

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