Removed AddonMenu sorting code, since Addons are order dependend they…

… should never be sorted

Meaning a skin pack with new graphics might shadow graphic files in
another skin pack. Adding a manual way to reorder addons via Peek_Up/Down keys
might be a good idea.

src/supertux/menu/addon_menu.cpp

@@ -93,14 +93,6 @@ AddonMenu::refresh()
   m_installed_addons = m_addon_manager.get_installed_addons();
   m_repository_addons = m_addon_manager.get_repository_addons();
 
-#ifdef GRUMBEL
-  std::sort(m_addons.begin(), m_addons.end(),
-            [](const Addon& lhs, const Addon& rhs)
-            {
-              return lhs.title < lhs.title;
-            });
-#endif
-
   rebuild_menu();
 }