ENH: Add another New() implementation enabled for non default construcible...

ENH: Add another New() implementation enabled for non default construcible TFunctor so as to get a nice warning (thanks to @aregimbeau for the patch)

Modules/Core/Functor/include/otbFunctorImageFilter.h

@@ -310,6 +310,17 @@ public:
     p->UnRegister();
     return p;
   }
+
+    /** New() macro defined only if TFunction is NOT default constructible
+     * This will yield an error message since New() can not be implemented in this case. */
+  template <typename F = TFunction> static std::enable_if_t<!std::is_default_constructible<F>::value, Pointer> New()
+  {
+    static_assert(std::is_default_constructible<F>::value,"Cannot call New() "
+      "methode as the functor used for the filter creation is not default "
+      "constructible");
+
+    return nullptr;
+  }
   
   /** Get the functor object.
    *