TDBM gains support for large volume transactions

Starting with version 3.3+, TDBM (Mouf's ORM) is gaining support for large volume processing, thanks to the weakref PHP extension!

Before version 3.3, the more record where fetched by TDBM, the more memory was consumed, until we ran out of memory. Hopefully, thanks to weakref support, unused beans are now freed from memory if they are no longer used. Therefore, you can now process large datasets (usually in batches) using TDBM!