[2.0][DDC-48][DDC-47] Refactored cache drivers to allow more control over deleting, added namespacing to cache drivers and implemented clear-cache task

[2.0] Fixed some known issues with inheritance, especially class table inheritance, like join columns not being selected.

[2.0] Fix for fix for testsuite ;). Need to find out why the behavior is different. sqlite versions? phpunit versions?

[2.0] Fix for test suite. It was trying to recreate association tables and they're not getting deleted. SchemaTool was trying to recreate them during some executions.

[2.0] Grammar rule fixes to prevent possibility to do key=field=identifier as a correct parseable grammar

[2.0] Fixed hydration issue with bidirectional one-to-many associations. Added more test coverage for some advanced association queries and lazy-loading.

[2.0][DDC-49][DDC-50][DDC-33] Fixed DDC-49 and DDC-50. Also addressed DDC-33. Various other small changes and fixes. For problems with proxy objects please refer to the updated documentation.

[2.0] DBAL cleanups (DDC-46). Proxy class improvements (DDC-19, DDC-39). Started new UPGRADE_TO document for upgrade instructions between advancing Doctrine 2 versions.

[2.0] Refactoring some common code in to the AnnotationDriver and creating PhpDriver for consistancy

[2.0][DDC-34] Fixing issue with duplicate association mappings when dealing with mapped super classes