Push a mark before the agenda can move point in a buffer

Patch by Andreas Seltenreich.

lisp/ChangeLog

@@ -1,5 +1,8 @@
 2010-04-27  Carsten Dominik  <carsten.dominik@gmail.com>
 
+	* org-agenda.el (org-agenda-goto): Push a mark before changing
+	the position.
+
 	* org-footnote.el (org-footnote): New group.
 	(org-footnote-section)
 	(org-footnote-tag-for-non-org-mode-files): Fix typos.

lisp/org-agenda.el

@@ -6082,6 +6082,7 @@ and by additional input from the age of a schedules or deadline entry."
 	 (pos (marker-position marker)))
     (switch-to-buffer-other-window buffer)
     (widen)
+    (push-mark)
     (goto-char pos)
     (when (org-mode-p)
       (org-show-context 'agenda)