Description:
------------
The trim function doesn't trim away whitespaces when giving it null value in the charlist.

Reproduce code:
---------------
function array_trim($arr, $charlist=null)
{
	if (is_array($arr))
	{
		foreach($arr as $key => $value)
		{
			if (is_array($value)) $result[$key] = array_trim($value, $charlist);
			else $result[$key] = trim($value, $charlist);
		}
		return $result; 
	}
}
var_dump(array_trim(array(' foo', 'bar ')));

Expected result:
----------------
array(2) {
  [0]=>
  string(3) "foo"
  [1]=>
  string(3) "bar"
}

Actual result:
--------------
array(2) {
  [0]=>
  string(4) " foo"
  [1]=>
  string(4) "bar "
}