Bugfix: include factor in subdiff

dune/tnnmg/functionals/semilinearfunctional.hh

@@ -217,7 +217,9 @@ public:
   auto subDifferential(double pos) const
   {
     auto shiftedPos = origin_ + pos;
-    return phi_.subDifferential(shiftedPos);
+    auto sd = phi_.subDifferential(shiftedPos);
+    sd *= weights_;
+    return sd;
   }
 
   Range operator()(Vector x) const