* giovabackup (log, version): updated.
(main): new --verbose option and log file support.
(print_env): new function to print conf values.
(mac_to_server):  --itemize-changes and rule of silence support.
* giovabackup:  remote unavailability management.
(is_remote_not_available): new function to test remote items.
(mac_to_server) update.