DietPi-Sync | Empty source check, dry run merge and minor fixes/enhancements

[MichaIng]

Status: Ready

• DietPi-Drive_Manager mount selection exit code and last item removal
• Changelog

Testing:

• VM Jessie
• VM Stretch
• VM Buster

Reference: #2602

Commit list/description:

• DietPi-Sync | Check and abort sync, if the source dir is empty, e.g. due to inactive mount point
• DietPi-Sync | Merge dry run into real sync, give a summary and allow user to continue, cancel or view the dry run log
• DietPi-Sync | Do not kill rsync processes, rely on systemctl to stop the service gracefully. Leave e.g. running syncs to end user to finish/handle, so we do no break anything unexpectedly.
• DietPi-Sync | Log to persistent /var/tmp/dietpi/logs instead of RAMlog, if target dir is not available
• DietPi-Sync | Move "--delete-excluded" option into delete mode selection, so with delete mode disabled, really nothing is removed from target dir.
• DietPi-Sync | Remove rsync "-h" option, since free space check expects bytes
• DietPi-Sync | Fix file count scrapes from dry run summary, since $6 and $8 do not necessarily match file and dir count, dependant on the existence of any file/dir/link/...
• DietPi-Sync | GUI: Use last chosen menu item as new default
• DietPi-Sync | Prevent theoretically possible menu loop, reverting to main menu in case of invalid integer
• DietPi-Sync | On mount list selection, only apply path, if an actual selection has been made: To be added to DietPi-Drive_Manager as well!
• DietPi-Sync | Minor coding and wording
• DietPi-Drive_Manager | RootFS_Move(): Failsafe root mount replacement if more than one space is between "/" and "auto"
• DietPi-Drive_Manager | RootFS_Move(): Do not automatically reboot, instead leave choice to user
• DietPi-Drive_Manager | Mount selection: Always remove old output file to prevent obsolete value in parent script in case of user cancel. Instead when user cancels selection, set EXIT_CODE=1 to be checked in parent script.
• DietPi-Drive_Manager | Prevent theoretically possible menu loop, reverting to main menu in case of invalid integer
• DietPi-Drive_Manager | Minor coding and wording
• DietPi-Backup | Prevent theoretically possible menu loop, reverting to main menu in case of invalid integer
• DietPi-Backup | Minor coding
• CHANGELOG | DietPi-Sync: Sync will abort now if the source dir is empty and merged dry run into real sync
• DietPi-Patch | Remove obsolete DietPi-Sync log