efl/gesture: add an event to notify when a config value has been changed

recognizers should be storing config values internally to avoid overhead
of multiple eo/hash lookups on every event

Reviewed-by: woochan lee <wc0917.lee@samsung.com>
Differential Revision: https://phab.enlightenment.org/D11174

src/lib/evas/gesture/efl_canvas_gesture_manager.c

@@ -142,6 +142,7 @@ _efl_canvas_gesture_manager_config_set(Eo *obj, Efl_Canvas_Gesture_Manager_Data
    v = eina_value_new(eina_value_type_get(value));
    eina_value_copy(value, v);
    eina_hash_add(pd->m_config, name, v);
+   efl_event_callback_call(obj, EFL_GESTURE_MANAGER_EVENT_CONFIG_CHANGED, (void*)name);
    if (!eina_streq(name, "glayer_tap_finger_size")) return;
    eina_value_get(value, &finger_size);
    _update_finger_sizes(pd, finger_size);

src/lib/evas/gesture/efl_canvas_gesture_manager.eo

@@ -43,6 +43,9 @@ class @beta Efl.Canvas.Gesture_Manager extends Efl.Object
          }
       }
    }
+   events {
+      config,changed: string; [[Called when a config value has been changed for the manager object. Passed string is the name of the value.]]
+   }
    implements {
       Efl.Object.constructor;
       Efl.Object.destructor;