add update method to ModelObject

kfet/static/kfet/js/kfet.api.js

@@ -137,14 +137,23 @@ class ModelObject {
      */
     from(data) {
         // TODO: add restrict
-        $.extend(this, this.constructor.default_data, data);
+        this.clear();
+        this.update(data);
+    }
+
+    /**
+     * Update properties of this instance from data ones.
+     * @param   {Object} data
+     */
+    update(data) {
+        $.extend(this, data);
     }
 
     /**
      * Clear properties to {@link Models.ModelObject.default_data|default_data}.
      */
     clear() {
-        this.from({});
+        $.extend(this, this.constructor.default_data);
     }