[2.0] DDC-239 - Added several new mapping validations for duplicate association/field and or column name definitions, and in combination with the discriminator column name.

[2.0] Code cleanups. Preparations for DDC-193. Fixed DDC-399, type configuration remains global for now but the irritating instance methods on the Configuration have been removed. Use Type::addType et al. Added TODOs for naming standards.

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

[2.0] DDC-268 - Exchanged DoctrineException for MappingException and added missing exception method (thanks to Christian Heinrich for the patch)

[2.0] DDC-115 - Proper fix of global namespace problem was in the ClassMetadataInfo, a namespace plus seperator was appended for reasons of shortcuts. However this broke associations in global namespace. Changes to ClassMetadataFactory were reverted and fix plus tests applied to ClassMetadataInfo.

[2.0] Fixed DDC-101, DDC-102 - Ensure defaults for string length and field nullability are handled consistently in both update and create schema commands of SchemaTool.

[2.0] Applied fixes for character casing issues. Simplified inheritance mapping and improved handling of outer joins in Class Table Inheritance.

[2.0] Fixed issues discovered during code coverage report generation. Made all ClassMetadata properties public (good reasons, read the class docblock). Performance improvements.

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).

added missing annotation driver class. small refactorings. added first ClassMetadata serialization tests.