def line_breadcrumb(action)
    referential_breadcrumb
    add_breadcrumb Chouette::Line.model_name.human(:count => 2), referential_lines_path(@referential) unless action == :index
    add_breadcrumb breadcrumb_label(@line), referential_line_path(@referential, @line),:title => breadcrumb_tooltip(@line) if action == :edit