minor enum_ improvement (use __repr__ instead of __str__)

include/pybind/pybind.h

@@ -813,7 +813,7 @@ public:
     enum_(object &scope, const char *name, const char *doc = nullptr)
       : class_<Type>(scope, name, doc), m_parent(scope) {
         auto entries = new std::unordered_map<int, const char *>();
-        this->def("__str__", [name, entries](Type value) -> std::string {
+        this->def("__repr__", [name, entries](Type value) -> std::string {
             auto it = entries->find((int) value);
             return std::string(name) + "." +
                 ((it == entries->end()) ? std::string("???")