[Dune] Constification & Reference Elements

[Christian Engwer]

Hi,

yesterday a short dicussion regarding the implementation of reference
elements started. Also we started (as you might have noticed due to
the cvs log messages) to work on final constification. The leads me to
an other point:

Please don't commit any changes to dune/grid/common until we are
finished with the constification. When we are done we will inform you
and also send you an introduction to the changes we made and an
overview how to move a grid to the new interface.

Please keep in mind, that the changes we decided on friday are quite
substantial so it wont be possible to automatically merge it with patch
in the trunk.

Cheers Christian.