removed superfluous part determination
fix for memory leaks in PHP ZendOpcache (verfied up to and including version 5.6.3 / opcache 7.0.4-dev)
@see bug report https://bugs.php.net/bug.php?id=65743: concerns ZendOpcache with "continue 2"
@see https://github.com/mtdowling/cron-expression/pull/51
Merge branch 'zendopcache-fix'