backup: pull subvol-list and grep-paths to subs
backup: clarify that 'out of order' means IDs and path-suffixes {dates} have a different sort order
backup: add a sub for parsing btrfs qgroup show + btrfs subvol list
backup: "rerunning as root" msg => STDERR
backup: add --info arg to print subvols and quota info
backup: add --quick arg to --info to skip quota re-enabling
backup: add --sort-by=[id|path|size] arg to --info
backup: downgrade deleted subvolumes to a warning
bashrc: add alias qgroups-info => backup --info