[zabbix][R] zabbix_sender sends multi-line value

https://support.zabbix.com/browse/ZBXNEXT-2158

[root@zbxsrv tmp]# zabbix_sender -s zbxsrv -z zbxsrv -k ‘test[1 2 3]’ -o $‘line 1\nline 2′ -v
info from server: “processed: 1; failed: 0; total: 1; seconds spent: 0.000076″
sent: 1; skipped: 0; total: 1