[Dune] Removal of GenericGeometry::normal()

[Christoph Grüninger]

Hi Oliver,
I think I did not move the test to dune-geometry because then it was not 
clear whether dune/geometry/genericgeometry/geometry.hh belongs to 
dune-geometry or dune-grid. Currently I don't see an obstacle to move 
the test. If you allow it, I'll move the test today or at least tomorrow.
Nevertheless, testmapping.cc and testgeo.cc still use headers from 
dune-grid.

Greets
Christoph

-- 
People who are more than casually interested in computers should have
at least some idea of what the underlying hardware is like. Otherwise
the programs they write will be pretty weird.         -- Donald Knuth