Add "NOT IN" filter in filterItems

[black-meridian]

components/migx/model/migx/migx.class.php

#2390
case 'notin':
$operand = is_array($operand) ? $operand : explode(',', $operand);
$output = !in_array($subject, $operand) ? $then : (isset($else) ? $else : '');
break;