This is necessary because pdo_sqlsrv still has some little bugs that
prevent it from being used in all use-cases. Additionally only sqlsrv
can make use of the Azure federations features.

Signed-off-by: Juozas Kaziukenas <juozas@juokaz.com>

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

DDC-496 Finished first versions of platform and schema manager for DB2, DDC-528 Added support for PDO_IBM driver, passing all but 3 tests that are related to CLOB fields

[2.0][DDC-284] Fixed. API polish and some convention over configuration simplifications for join columns and join tables.

[2.0] DDC-92 - Refactored Doctrine\DBAL\DriverManager some more in regards to exceptions and added some more test-cases.

[2.0] DDC-92 - Removed DoctrineException from Doctrine\DBAL\DriverManager and replaced with more specific DBALException's

[2.0] Implemented DQL bulk DELETE support for Class Table Inheritance. Other cleanups, refactorings and docblock additions.