Add natural mapping
Same as https://github.com/ufz/ogs/pull/205 with additions by Tom and me.
What is missing in our opinion are the test documentation especially for the NumLibFemNaturalCoordinatesMappingQuad4Test, which has a non-trivial setup.
Same as https://github.com/ufz/ogs/pull/205 with additions by Tom and me.
What is missing in our opinion are the test documentation especially for the NumLibFemNaturalCoordinatesMappingQuad4Test, which has a non-trivial setup.