Description:
------------
Using named paramters with the "IN" statement does not work correctly. Is a list is used as a parameter with bindValue this list is interpreted as a quoted string in the sql command

Reproduce code:
---------------
$arrEmployees = array(1,2,3,4,5,6);

$strSQL = "
   SELECT id, name
   FROM   employees
   WHERE  id in (:my_list);
";

$objPDOStatement = $objPDO->prepare($strSQL);
$objPDOStatement -> bindValue(':my_list', implode(',', $arrEmployees));
$objPDOStatement -> execute();

Expected result:
----------------
--------------
id | name
--------------
 1 | John Doe
 2 | Jack Doe
 3 | Gill Doe
 4 | Ralf Doe
 5 | Sven Doe
 6 | Carl Doe
--------------

Actual result:
--------------
--------------
id | name
--------------
 1 | John Doe
--------------

In sql cli, same results as if running  

   SELECT id, name
   FROM   employees
   WHERE  id in ('1,2,3,4,5,6'); -- List with quotes;

when expecting

   SELECT id, name
   FROM   employees
   WHERE  id in (1,2,3,4,5,6); -- List with no quotes;