Wordpress Cleanup wp_nav_menu Classes

functions.php

// Cleanup some of the extra menu item classes added to wp_nav_menu
function nh_allowed_menu_item_classes($classes, $item) {

    // Get custom classes added from within the menus admin page
    $new_classes = (array) get_post_meta( $item->ID, '_menu_item_classes', true );

    // Consolidate the assorted "current..." classes
    $current_classes = preg_grep('/current/', $classes);
    if(!empty($current_classes)) $new_classes[] = 'current';

    return $new_classes;
}
add_filter('nav_menu_css_class', 'nh_allowed_menu_item_classes', 10, 2);