[gtkmm] Gtk::AccelKey, MenuItem: Remove obsolete code and comments

[Kjell Ahlstedt <kjellahl src gnome org>]

commit 45e2ed732a65c055acc380e0a744f31e22e420d8
Author: Kjell Ahlstedt <kjellahlstedt gmail com>
Date:   Mon Nov 27 15:27:01 2017 +0100

    Gtk::AccelKey, MenuItem: Remove obsolete code and comments
    
    such as the empty namespace Gtk::Menu_Helpers and some comments.

 gtk/gtkmm/accelkey.h |    9 +++------
 gtk/src/menuitem.ccg |    8 --------
 gtk/src/menuitem.hg  |    4 ----
 3 files changed, 3 insertions(+), 18 deletions(-)
---
diff --git a/gtk/gtkmm/accelkey.h b/gtk/gtkmm/accelkey.h
index 42c19a3..0e9f42e 100644
--- a/gtk/gtkmm/accelkey.h
+++ b/gtk/gtkmm/accelkey.h
@@ -1,9 +1,7 @@
 #ifndef _GTKMM_ACCELKEY_H
 #define _GTKMM_ACCELKEY_H
 
-/* menu_elems.h
- *
- * Copyright (C) 1998-2002 The gtkmm Development Team
+/* Copyright (C) 1998-2002 The gtkmm Development Team
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -29,11 +27,10 @@ namespace Gtk
 
 /** Defines accelerator key combinations.
  * For instance, pressing Control-Q to activate the File|Quit menu item.
- * Typedefed as Gtk::Menu::AccelKey
  *
  * By defining accelerator paths you can allow the user of your application
  * to change accelerators himself. An example of an accelerator might be
- * "<MainWindow>/File/Open". Modified accelerators may be saved
+ * "<MainWindow>/File/Open". Modified accelerators may be saved.
  * @see Gtk::AccelMap
  * @ingroup Menus
  */
@@ -48,7 +45,7 @@ public:
   * @param accel_path For instance, "<MainWindow>/File/Open"
   */
   AccelKey(guint accel_key, Gdk::ModifierType accel_mods,
-           const Glib::ustring& accel_path = "");
+           const Glib::ustring& accel_path = Glib::ustring());
 
   /** AccelKey constructor.
    * @param accelerator For instance, &quot;&lt;control&gt;q&quot; - Use
diff --git a/gtk/src/menuitem.ccg b/gtk/src/menuitem.ccg
index 0d35447..5cd7242 100644
--- a/gtk/src/menuitem.ccg
+++ b/gtk/src/menuitem.ccg
@@ -17,21 +17,13 @@
  */
 
 #include <gtk/gtk.h>
-#include <gtkmm/label.h>
 #include <gtkmm/menu.h>
-#include <gtkmm/box.h>
 #include <gtkmm/window.h>
-#include <gtkmm/menubar.h>
 #include <gtkmm/accelmap.h>
-#include <gtkmm/accelgroup.h>
-
-// gtk_menu_item_(de)select are just a wrapper for gtk_item_(de)select
-// and defined in Gtk_Item, so they do not be redefined here
 
 namespace Gtk
 {
 
-
 MenuItem::MenuItem(Widget& widget)
 :
   _CONSTRUCT()
diff --git a/gtk/src/menuitem.hg b/gtk/src/menuitem.hg
index ffa5171..205ff37 100644
--- a/gtk/src/menuitem.hg
+++ b/gtk/src/menuitem.hg
@@ -30,7 +30,6 @@ namespace Gtk
 {
 
 class Menu;
-namespace Menu_Helpers { class Element; }
 
 /** Child item for menus.
  * Handle highlighting, alignment, events and submenus.
@@ -101,9 +100,6 @@ protected:
   void set_accel_key(const AccelKey& accel_key);
 
 private:
-  friend class Menu_Helpers::Element;
-
-  //This data is set by MenuElem, and will be used in on_realize(), in the call to add_accelerator().
   AccelKey accel_key_;
 };