Add deprecation warnings for old matrixtraits and scalartraits includes.

dune/matrix-vector/matrixtraits.hh

+#ifndef DUNE_MATRIX_VECTOR_MATRIXTRAITS_HH
+#define DUNE_MATRIX_VECTOR_MATRIXTRAITS_HH
+
+#include <dune/matrix-vector/traits/matrixtraits.hh>
+
+#warning \
+  This file is deprecated and might vanish soon. \
+  Please use Dune::MatrixVector::Traits::MatrixTraits \
+  from <dune/matrix-vector/traits/matrixtraits.hh> instead \
+  or the trait utilities in namespace Dune::MatrixVector \
+  to be included via <dune/matrix-vector/traits/utilities.hh>.
+
+namespace Dune { namespace MatrixVector {
+
+template <class T>
+using MatrixTraits = Traits::MatrixTraits<T>;
+
+}}
+
+#endif // DUNE_MATRIX_VECTOR_MATRIXTRAITS_HH

dune/matrix-vector/scalartraits.hh

+#ifndef DUNE_MATRIX_VECTOR_SCALARTRAITS_HH
+#define DUNE_MATRIX_VECTOR_SCALARTRAITS_HH
+
+#include <dune/matrix-vector/traits/scalartraits.hh>
+
+#warning \
+  This file is deprecated and might vanish soon. \
+  Please use Dune::MatrixVector::Traits::ScalarTraits \
+  from <dune/matrix-vector/traits/scalartraits.hh> instead \
+  or the trait utilities in namespace Dune::MatrixVector \
+  to be included via <dune/matrix-vector/traits/utilities.hh>.
+
+namespace Dune { namespace MatrixVector {
+
+template <class T>
+using ScalarTraits = Traits::ScalarTraits<T>;
+
+}}
+
+#endif // DUNE_MATRIX_VECTOR_SCALARTRAITS_HH