Persist File Backup Improvements

Added support for "backup file rolling" - if the backup file extension includes a %N then we will do automatic file rolling. Replacing the %N with 1,2,3,... to the maximum number of backups requested (5 default). I made this mode the default mode.

Also includes some cherry-picked warning fixes.
I'm guessing this change to a backup every minute was a change for rapid testing and should be returned to 30 min.