icalendar: Take care of multiple vcalendars in a single file.

icalendar: Take care of multiple vcalendars in a single file.

lisp/ChangeLog:

	* calendar/icalendar.el (icalendar--all-events): Take care of
	multiple vcalendars in a single file.
	(icalendar--convert-float-to-ical): checkdoc fixes.

	* automated/icalendar-tests.el (icalendar-tests--compare-strings):
	Removed, simply use string=.
	(icalendar--diarytime-to-isotime)
	(icalendar--datetime-to-diary-date)
	(icalendar--datestring-to-isodate)
	(icalendar--format-ical-event)
	(icalendar--parse-summary-and-rest)
	(icalendar-tests--do-test-import)
	(icalendar-tests--do-test-cycle) : Changed argument order of
	string= to EXPECTED ACTUAL.
	(icalendar--import-format-sample)
	(icalendar--format-ical-event)
	(icalendar-import-non-recurring)
	(icalendar-import-rrule)
	(icalendar-import-duration)
	(icalendar-import-bug-6766)
	(icalendar-real-world): Adjusted to string= instead of
	icalendar-tests--compare-strings.
	(icalendar-import-multiple-vcalendars): New.