Functions based on same category not work

When I use
previous_post_link( '&laquo; %link', '%title', true, '', 'category' ); ?> | <?php next_post_link( '%link &raquo;', '%title', true, '', 'category' );
in my custom theme, then the parameter true/category was not working, because your plugin override the where filters and do not pay attention to this parameters.

I override these functions in my function.php so the prev/next_post_link functions are working (and also are ordered by the menu_order. Hope you can implement it to your plugin.

function ify_prevnext_post_join(){
    global $post, $wpdb;
    return " INNER JOIN $wpdb->term_relationships AS tr 
    ON p.ID = tr.object_id 
       INNER JOIN $wpdb->term_taxonomy tt 
    ON tr.term_taxonomy_id = tt.term_taxonomy_id ";
}
add_filter('get_previous_post_join', 'ify_prevnext_post_join');
add_filter('get_next_post_join', 'ify_prevnext_post_join');
 function ify_previous_post_where() {
    global $post, $wpdb;
    $cat_array = wp_get_object_terms($post->ID, 'category', array('fields' => 'ids'));
    $posts_in_ex_cats_sql = " AND tt.taxonomy = 'category' AND tt.term_id IN (" . implode(',', $cat_array) . ") "; 
	return $wpdb->prepare( "WHERE p.menu_order < %s AND p.post_type = %s AND p.post_status = 'publish' $posts_in_ex_cats_sql ", $post->menu_order, $post->post_type);
}
add_filter( 'get_previous_post_where', 'ify_previous_post_where' );
function ify_next_post_where() {
    global $post, $wpdb;
    $cat_array = wp_get_object_terms($post->ID, 'category', array('fields' => 'ids'));
    $posts_in_ex_cats_sql = " AND tt.taxonomy = 'category' AND tt.term_id IN (" . implode(',', $cat_array) . ") "; 
	return $wpdb->prepare( "WHERE p.menu_order > %s AND p.post_type = %s AND p.post_status = 'publish' $posts_in_ex_cats_sql ", $post->menu_order, $post->post_type);
}
add_filter( 'get_next_post_where', 'ify_next_post_where' );
function ify_previous_post_sort() {
	return "ORDER BY p.menu_order desc LIMIT 1";
}
add_filter( 'get_previous_post_sort', 'ify_previous_post_sort' );
function ify_next_post_sort() {
	return "ORDER BY p.menu_order asc LIMIT 1";
}
add_filter( 'get_next_post_sort', 'ify_next_post_sort' );