Add PluginConfigDialog, EditorPluginSettings GUI

editor/project_settings_editor.h

@@ -188,6 +188,7 @@ public:
 	static ProjectSettingsEditor *get_singleton() { return singleton; }
 	void popup_project_settings();
 	void set_plugins_page();
+	void update_plugins();
 
 	EditorAutoloadSettings *get_autoload_settings() { return autoload_settings; }