def network_breadcrumb(action)
    referential_breadcrumb
    add_breadcrumb Chouette::Network.model_name.human(:count => 2), referential_networks_path(@referential) unless action == :index
    add_breadcrumb breadcrumb_label(@network), referential_line_path(@referential, @network),:title => breadcrumb_tooltip(@network) if action == :edit