Drop obsolete inheritance

dune/tectonic/nicefunction.hh

@@ -9,7 +9,7 @@
 #include <dune/common/function.hh>
 
 namespace Dune {
-class NiceFunction : public VirtualFunction<double, double> {
+class NiceFunction {
 public:
   virtual ~NiceFunction() {}
 
@@ -26,6 +26,8 @@ class NiceFunction : public VirtualFunction<double, double> {
 
   // Whether H(|.|) is smooth at zero
   bool virtual smoothesNorm() const { return false; }
+
+  void virtual evaluate(double const &x, double &y) const = 0;
 };
 
 class RuinaFunction : public NiceFunction {