DDC-515 - Enhanced Validate-Schema-Command, integrated it with CLI and besides mapping<->database checks also do consistency checks of the mapping files

Also added a new testcase

Conflicts:

	lib/Doctrine/ORM/Mapping/Driver/XmlDriver.php

Removed EntityTransaction until it has a real purpose. Added the affected entity to OptimisticLockException. Updated functional optimistic locking tests accordingly.

Renamed fetchRow to fetchAssoc, as defined in @todo list. Renamed getRollbackOnly to isRollbackOnly, since it is more consistent to its purpose.

Revertd partially the support to DBAL\Transaction, it was wrong. Fixed implementation of ORM\EntityTransaction and fixed tests.

Added tests for 41e830ca, thereby finding two issues with XML and YAML Driver handling of Sequence-Generator