Calculate strlen($salt) in _consistent_shuffle only once
Calculate strlen($salt) in _consistent_shuffle only once

This commit speeds up both encoding and decoding by 19%

einice/hashids.php,ksmylz/hashids.php,jorik041/hashids.php,jkramarz/hashids.php,vinkla/hashids,dayed/hashids.php,ivanakimov/hashids.php