#283 Retry / reconnect on network errors during check

[Fernando Lozano]

During a full backup contaiing hundeds of GB, there was a transient network error, and the SFTP (SSH) connection was lost. This happened during the "check after backup" and so Areca deleted (rolled back) a good backup archive which took hours to make.

Areca could be more resilient to such erros, trying to reconnect a few times, maybe with a few seconds interval between each try.

So far I disabled "check after backup" and am peforming a scheduled check from another job. But I wonder the same could happen during backup (or a manual/scheduled check).

During backup, it should be able to automatically continue the job, after reconnecting, if the configuration uses transaction points.