When expanding, ignore events that are recurring but have 0 valid
recurrence instances.

Fixes #168.
The new php codesniffer is stricter ;)
Making sure this unittest doesn't break in some PHP versions.
Releasing vobject 2.1.6.
Merge branch '2.1' into 3.3

Conflicts:
	ChangeLog
	lib/Version.php
	tests/VObject/TimeZoneUtilTest.php
Unused code.
Suggestions from sensiolabs insight.
Merge branch '3.3'

Conflicts:
	ChangeLog.md
	lib/Version.php
	lib/timezonedata/php-bc.php