DoctrineMySQLComeBack 2.0.0: DBAL 3 support

The facile-it/doctrine-mysql-come-back was written long time ago by my colleague Luca Boeri, in an attempt to solve the infamous “MySQL server has gone away” error, and similar issues. It’s a simple Doctrine DBAL driver wrapper that catches relevant exceptions from the driver and attempts to reconnect to the database; this is pretty useful if your PHP script is doing something else between queries, and an aggressive timeout from the database truncates the connection in the meantime, due to the prolonged inactivity.