org-agenda.el: Make sure to get a property from (1- (point-max)), not (point-max))

org-agenda.el: Make sure to get a property from (1- (point-max)), not (point-max))

* org-agenda.el (org-agenda-manipulate-query)
(org-agenda-goto-date, org-agenda-goto-today)
(org-agenda-find-same-or-today-or-agenda, )
(org-agenda-later, org-agenda-change-time-span)
(org-agenda-change-all-lines)
(org-agenda-execute-calendar-command)
(org-agenda-goto-calendar, org-agenda-convert-date): Make sure
to get a property from (1- (point-max)), not (point-max)).

Thanks to Juan Pechiar for reporting a related problem.