conforming grids.

due to unstable and incomplete implementation practices.

GenericGeometry backport.

The current fix is to throw Dune::NotImplemented, though

NOTE: 'make test' was replaced by 'make build_tests && make test'

This reverts commit af3fde69.

are stored using std::unique_ptr.

[feature] Allow construction of simplices using different simplex element types (only for bisection refinement).

bisection refinement.

the test refines a 3d ball with a projection
and calculates the error to the real ball
this should reduce over refinement

With this patch, Entity::father, Entity::subEntity,
IntersectionIteratorWrapper::inside and IntersectionIteratorWrapper::outside
return entities instead of entity pointers.

Warning: This will definitely break compatibility with the 2.3 release.