fixed start date

[yul11]

A fixed date would be helpful to automatically produce an incremental backup
(after a full backup is made on this date). The problem is: Say, someone
copies or moves files, say one week old, into the folder which has to be
"backupped". An e.g. daily backup of the last one day will not backup these
files!

[Zenju]

See the discussion here:
viewtopic.php?t=1924

[yul11]

I continue on the proposed topic "date range selections":
viewtopic.php?t=1924