* calendar/todos.el (todos-undo-item-omit-comment): New defcustom.

* calendar/todos.el (todos-undo-item-omit-comment): New defcustom.
(todos-item-undo): Use it.
(todos-allcats-file, todos-all-categories-alist): New variables.
(todos-all-categories-alist): New function.
(todos-jump-to-any-category): New command.
(todos-move-item): Remove mark overlays from buffer items were
moved from; update todos-categories-with-marks,