Declare a variable explicitly in order to prevent from E_NOTICE

[aazon]

We have a lot of notices like the following one:

PHP Notice:  Only variable references should be returned by reference in /path_to_project/vendor/fieryprophet/php-sandbox/src/functions.php on line 44

We are running php 5.6:

php -v
PHP 5.6.5 (cli) (built: Jan 21 2015 17:50:29)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.6.0, Copyright (c) 1998-2014 Zend Technologies
    with Zend OPcache v7.0.4-dev, Copyright (c) 1999-2014, by Zend Technologies

Looks like php does not like return new Foo() in functions like &wrapByRef and wants some variable to be returned instead.

[fieryprophet]

I appreciate the pull request and have incorporated it into the latest build.