* lisp/ox-icalendar.el (org-icalendar-entry): Use
`org-icalendar-with-timestamps'.
We cannot simply rely on ignored timestamps in communication channels,
as regular `org-export-with-timestamps' only applies to isolated
timestamps.
Thanks to Greg Troxel for reporting it.
http://permalink.gmane.org/gmane.emacs.orgmode/85387