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

[2.0] More general work on the SchemaManager and Platform classes. Making API more complete and adding sqlite and mysql test coverage.

[2.0] Fixes and enhancements to sequence generators. Test suite now runs & passes against postgres. Other minor, unrelated cleanups.

[2.0] Moved code between Query and AbstractQuery. Added first NativeQuery implementation. Hydration work and code movements for discriminator column usage. Started implementing Single Table Inheritance.

First tests for basic collection implementation. First experimental use of closures (Currently commented out, because the svn server makes a syntax check against 5.2.x).