Validate driver options

[gajus]

Doll implementation uses delayed initialisation, which in effect does not allow to catch invalid driver attributes before the database connection is established. This might prove a trouble. If it does, then use ReflectionClass to make sure that driver attributes are valid at the time of instantiating Doll instance:

$pdo_reflecation = new \ReflectionClass('PDO');
$pdo_reflecation->getConstants();