Add initial ability to reorder entries in a group; allow groups to contain both entities and subgroups.
And bugfix: attempt to correct "of N more" on lists in UI.
New menu for more efficient group entry manipulation.
Bugfixes, and make new entry in group be sorted immediately after the selected one.
Rename table subgroup to groupsinagroup (prep for next work).
Continued/broken/overcomplicated attempt at modeling flexible subgroups as a separate thing,
when it seems better instead to rollback some(?) things from a few prior commits
and just use entities which contain groups, and put the rest of the smarts &
convenience in the UI.  Should go much faster since less code will have to
be written.
Revert "Continued/broken/overcomplicated attempt at modeling flexible subgroups as a separate thing,"

This reverts commit 0072e950bd0e475e4a52accad58f904290723881.
Revert "Rename table subgroup to groupsinagroup (prep for next work)."

This reverts commit 0b79e05bab39cdff3ad4927c23656e964522b54d.
Revert *parts of*:  "Bugfixes, and make new entry in group be sorted immediately after the selected one."

This reverts PART OF commit ad345e0e0f0bc97b61b89d5e22142031f63827f4.
Clean up the subgroup stuff to prep & do a simpler approach.
Bugfixes, including around archived objects; & more simplification.
Remove some comments w/ ideas & false starts.