(boolean): Capitalize "toggle".

(boolean): Capitalize "toggle".
(choice): Capitalize "value menu".
(visibility): Capitalize "hide" and "show".
(group-visibility): Likewise.
(widget-documentation-string-value-create): Capitalize "more".

(widget-specify-insert): Bind before-change-functions.
(widget-insert, widget-setup): Likewise.
(widget-editable-list-delete-at, widget-default-delete): Likewise.
(widget-editable-list-insert-before): Likewise.
(widget-setup): Set up before-change-functions.
(widget-after-change): Don't apply :notify here.
(widget-before-change): New function.  Apply :notify here.
(group-link): New widget type.
(widget-group-link-action): New function.
(widget-group-link-create): New function.

(group-visibility): New widget type.