added comment to append_menu_item and append_submenu.
added comment to append_menu_item and append_submenu.

lordofhyphens/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,lordofhyphens/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,lordofhyphens/Slic3r,pieis2pi/Slic3r,lordofhyphens/Slic3r,curieos/Slic3r,alexrj/Slic3r,lordofhyphens/Slic3r,lordofhyphens/Slic3r,alexrj/Slic3r,pieis2pi/Slic3r,curieos/Slic3r,curieos/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r,alexrj/Slic3r,curieos/Slic3r,pieis2pi/Slic3r,alexrj/Slic3r