Reworked type-based and conditions and clarified some types to justify the ones that remain unchanged.

Removed the `Dbal` prefix from the class names and moved them to the `Doctrine\Tests\DBAL` namespace.

This PR introduces a new PingableConnection interface and exposes
a ping method on \Doctrine\DBAL\Connection. For drivers where no
ping is supported, a \Doctrine\DBAL\ConnectionException is thrown.

 * test case to assert the connection timeout is set
 * test case to assert on exceptions thrown
   * wip, as it seems impossible to trigger 'false' from mysqli_options