🐛 Adding php56 compatibility

[macoaure]

The short syntax for the 'list' function was introduced in PHP 7.1. Prior to this version, 'list' was used as a regular function. Our Magento 1.5 projects are currently running on PHP 5.6, which does not support the short syntax. This has resulted in the following error:

<?php

// works
list($a, $b) = [
    'a',
    'b'
];

// dont work
[$a, $b] = [
    'a',
    'b'
];

// Parse error: syntax error, unexpected '=' in /.../test.php on line 10

[colinmollenhour]

Thanks for the PR. PHP 5.6 support is not really a goal but I'll try to keep this in mind.