def group_of_line_breadcrumb(action)
    referential_breadcrumb
    add_breadcrumb Chouette::GroupOfLine.model_name.human(:count => 2), referential_group_of_lines_path(@referential) unless action == :index
    add_breadcrumb breadcrumb_label(@group_of_line), referential_group_of_line_path(@referential, @group_of_line),:title => breadcrumb_tooltip(@group_of_line) if action == :edit