[Dune] unitOuterNormal()

[Carsten Gräser]

Dear all,
as decided on the dune meeting yesterday we will introduce a method
on intersections returning the unit outer normal at the 'center'.
This must not be the exact centroid but should coincide with
the result of the new center() method on geometries. The proposed
name was 'unitOuterNormal()' without arguments.

There was one concern that this might be misunderstood (e.g. by students)
to return 'the normal' which does not exist in general. I suggest
to change the name to centerUnitOuterNormal() to prevent this issue.
Furthermore it describes exactly what the method is supposed to do.

Regards
Carsten

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Carsten Gräser           | phone: +49-30 / 838-75349
Freie Universität Berlin | fax  : +49-30 / 838-54977
Institut für Mathematik  | email: graeser at math.fu-berlin.de
Arnimallee 6             |
14195 Berlin, Germany    | URL  : http://page.mi.fu-berlin.de/graeser
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