0021014: EDF 1583 SMESH: Improvement of the Python Dump for the creation of groups

0021014: EDF 1583 SMESH: Improvement of the Python Dump for the creation of groups
   class Filter_i
   {
+    struct TPredicateChangeWaiter
+    {
+      virtual void PredicateChanged() = 0;
+    };
+    void AddWaiter( TPredicateChangeWaiter* waiter );
+    void RemoveWaiter( TPredicateChangeWaiter* waiter );

+    std::list<TPredicateChangeWaiter*> myWaiters;

+  const char*        FunctorTypeToString(SMESH::FunctorType ft);
+  SMESH::FunctorType StringToFunctorType(const char*       str);