(cua--undo-list, cua--tidy-undo-counter)

(cua--undo-list, cua--tidy-undo-counter)
(cua--rect-undo, cua--tidy-undo-lists, cua--rectangle-on-off): Remove.
(cua--rect-undo-set-point): New var.
(cua--rectangle-undo-boundary): Setup undo apply entry.
(cua--rect-undo-handler): New function for rectangle undo.
(cua--rect-start-position, cua--rect-end-position): Add.
(cua--rectangle-post-command): Call cua--rectangle-set-corners
for restored rectangle.  Set point if cua--rect-undo-set-point.