[2.0][DDC-122][DDC-97][DDC-98][DDC-147] Refactored metadata mapping drivers by removing the useless PRELOAD mode. Introduced ClassMetadataFactory#getAllMetadata. Classloader simplifications. Old classloaders deprecated. New Doctrine\Common\ClassLoader is almost the same as the previous IsolatedClassLoader.

[2.0] Fixed PHP Notice in SchemaTest (only variables should be passed by reference...) and a few other cosmetics in various parts.

[2.0][DDC-164][DDC-165] Fixed. Cleaned up ManyToManyMapping. Cleaned up identifier handling and handling of composite identifiers in some places.

[2.0][DDC-22] Fixed. Also cleaned up association handling. More to come: exception refactorings, proxy simplifications (single proxy class, not two).

[2.0] Small refactorings on the cache drivers. Introduced flag to control whether the cache driver should manage the cache keys since this is an advanced feature that is not always needed and can have negative side-effects (higher probability for cache slams).

[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] fixes #2478 Now PersistentCollections may contain NEW elements and track policy monitor them when flushing on DEFER_IMPLICIT mode

[2.0] Work on CLI: Added SchemaToolTask with preliminary support for dropping/creating the database schema. Prepared the sandbox. Adjusted build to include the sandbox.

[2.0] Moved beginTransaction() in UnitOfWork#commit() out of the try block so that exceptions occuring during prior or on transaction start are not masked by another exception.

[2.0] More preparations to fix character casing issue. Reverted and completed ConditionalPrimary parsing and added more tests for this.

[2.0] Fixed several referential integrity issues. Fixed critical issue with inserts being run twice on postgresql/oracle. Added support for additional tree walkers that modify the AST prior to SQL construction and started to play with it in a testcase.

[2.0] Removed AssociationMappings from ResultSetMapping  for improved caching. Fixed caching issue with reflection classes and properties. Reimplemented and leaned up broken identifier quoting. Added support for named (native) queries. Fixed small hydration memory leak.

[2.0] More cleanups for recent lazy-loading implementation and minor object hydration improvements and cleanups. Collection refactoring part I for ticket #2352.

[2.0] completed implementation of lazy loading for Collections. Created debug helper class. Fixed default for orderBy clause to ASC