Fix error in surfacecosseratenergy

The contravariant base vectors were not calculated correctly. The contravariant base vectors are the columns of the inverse of the covariant matrix, not the rows. To fix this, take the rows of the transpose of inverse of the covariant matrix.

dune/gfe/surfacecosseratenergy.hh

@@ -263,6 +263,9 @@ RT energy(const typename Basis::LocalView& localView,
 
       auto aContravariant = aCovariant;
       aContravariant.invert();
+      // The contravariant base vectors are the *columns* of the inverse of the covariant matrix
+      // To get an easier access to the columns, we use the transpose of the contravariant matrix
+      aContravariant = Dune::GFE::transpose(aContravariant);
 
       Dune::FieldMatrix<double,3,3> a(0);
       for (int alpha=0; alpha<boundaryDim; alpha++)