Function: format-annotate-single-property-change

Return annotations for property PROP changing from OLD to NEW.
These are searched for in the translations alist TRANSLATIONS
(see `format-annotate-region' for the format).
If NEW does not appear in the list, but there is a default function,
then call that function.
Return a cons of the form (CLOSE . OPEN)
where CLOSE is a list of annotations to close
and OPEN is a list of annotations to open.

The annotations in CLOSE and OPEN need not be strings.
They can be whatever the FORMAT-FN in `format-annotate-region'
can handle. If that is `enriched-make-annotation', they can be
either strings, or lists of the form (PARAMETER VALUE).