Description:
------------
It would be nice if you could affect the behaviour of casting an ArrayObject to an array by overloading the getArrayCopy() method.

This would be usefull to create lazy load arrays.

Reproduce code:
---------------
<?php

class Items extends ArrayObject
{
	/**
	 * Stub for loading an item.
	 * @return object
	 */
	public function load($id)
	{
		return (object)(array('id'=>$id));
	}

	public function offsetGet($key)
	{
		$item = parent::offsetGet($key);
		if (!is_object($item)) {
			$item = $this->load($item);
			$this->offsetSet($key, $item);
		}
		return $item;
	}
	
	public function getArrayCopy()
	{
		$array = parent::getArrayCopy();
		foreach ($array as $i=>&$item) {
			if (!is_object($item)) {
				$item = $this->load($item);
				$this->offsetSet($i, $item);
			}
		}
		return $array;
	}
}

$a = new Items();
$a[] = 'jan';
$a[] = 'piet';

var_dump($a[0]);
var_dump((array)$a);

Expected result:
----------------
object(stdClass)#2 (1) {
  ["id"]=>
  string(3) "jan"
}
array(2) {
  [0]=>
  object(stdClass)#2 (1) {
    ["id"]=>
    string(3) "jan"
  }
  [1]=>
  object(stdClass)#3 (1) {
    ["id"]=>
    string(4) "piet"
  }
}


Actual result:
--------------
object(stdClass)#2 (1) {
  ["id"]=>
  string(3) "jan"
}
array(2) {
  [0]=>
  object(stdClass)#2 (1) {
    ["id"]=>
    string(3) "jan"
  }
  [1]=>
  string(4) "piet"
}