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++)