[2.0] Adding DriverChain mapping driver type to allow you to configure drivers to use for certain entity namespaces

[2.0][DDC-366] Fixed. Fully qualified names were borked in the lexer as well. Tests didnt catch it because of unfortunate namespace constellations. Fixed now.

[2.0][DDC-364] Added Doctrine\Common\Version which provides the current version of Doctrine. Also added CLI tasks for Common and DBAL, since they may vary in the future.

[2.0][DDC-362] Fixed missing namespace declaration on __call method of EntityRepository. Thanks Marcel Walter for the patch.

[2.0] DDC-358 - Refactored UnitOfWork Event triggering capabilities -  Revert preUpdate change - Its not good!

[2.0] DDC-358 - Refactored UnitOfWork Event triggering capabilities -  Removed check for EntityManager instance. This is deep in the code and can hardly be get wrong.

[2.0] Applied convention over configuration using default cache implementation if none is defined in AnnotationReader.

[2.0] DDC-338 - Changed DQL Parser to comply with ordered collections when they are fetch joined (OMG, thanks to roman and guilherme for the detailed discussion on how to implement this)

[2.0][DDC-316][DDC-346] Implemented support to first result and max results aswell as different hydration mode support in orm:run-dql task

[2.0] DDC-336 DDC-337 - Changed @OrderBy annotation to take a DQL not SQL snippet, restrict it to field names and positional orderings. Changed all test-cases and added a test-case that shows the behaviour for OneToMany JoinedSubclassPersister Managed Entities.

[2.0] DDC-337 - Collections that are fetched through StandardEntityPersister and ordered are sorted by any given ORDER BY snippet. Now only the DQL Parser is missing in this regard.

[2.0] DDC-337 - Collections that are fetched through StandardEntityPersister and ordered are sorted by any given ORDER BY snippet. Now only the DQL Parser is missing in this regard.

[2.0] DDC-336 - Support specification of an OrderBy SQL snippet in OneToMany and ManyToMany Associations in Annotation, XML and YAML Drivers

[2.0]  DDC-330 - Fix SIZE(collectionValueExpression) using a COUNT(field) to COUNT(*) because in many to many scenarios and with several join columns a COUNT(fieldA, fieldB) would have been generated, which is not valid sql.

[2.0] DOCS - Example on using multiple entities in FROM clause, added test for this sql generation also, since it seems this was untested before.

[2.0] DDC-135 DDC-177 Implement missing WITH clause, disallow use of ON clause by throwing an exception

[2.0] DDC-321, DDC-323, DDC-324 - Implemented way to define UDFs from PHP in Sqlite Driver and registered to required default callbacks for SQRT and MOD, allowing functional tests for DQL MOD and SQRT to pass for all platforms.