Description:
------------
There seems to be a memory leak using Lua.

Test script:
---------------
<?
$cnt=0;
$total=100000;
$lastperc=-1;
for ($z=0;$z<$total;$z++) {
  $cnt++;

  $perc=round($cnt/$total*100);
  if ($perc!=$lastperc) {
    echo memory_get_usage(true)." Bytes<br />";
    echo $perc."%<br />";
    $lastperc=$perc;
    flush();
  }
  
  $lua=new Lua();
  $r=$lua->eval("return 2+5");
}
?>

Expected result:
----------------
I would expect the memory usage not rise indefinitely but instead stay constant.

Actual result:
--------------
The memory usage keeps increasing.