[2.0][DDC-254] Improved MappingException thrown on missing required configuration of Many-Many mapping

DDC-179 - Use ! modifier in Date Format to reset all non-date parts to zero unix timestamp values, i.e. H:i:s => '00:00:00' always

[2.0][DDC-236] Enhanced unique constraints to support names. Fixed general issues on XML and YAML exporters. Fixed issues on XML, YAML, Doctrine 1.X and Annotation drivers.

[2.0][DDC-236] Enhanced unique constraints to support names. Fixed general issues on XML and YAML exporters. Fixed issues on XML, YAML, Doctrine 1.X and Annotation drivers.

[2.0][DDC-234] Fixed issue with EntityRepository that was not considering alias of root Entity when instantiating a new QueryBuilder

[2.0][DDC-240] Fixed issue with StandardEntityPersister that was attempting to delete Entities based on field names instead of column names.

[2.0][DDC-237][DDC-216] Fixed. If you're using manual proxy generation through the CLI, please regenerate your proxies.

[2.0] Refactorings in DQL parser to allow more granular enhancements scheduled for later versions. Fixed issues with missing validations of invalid ResultVariable, Unknown query components and Re-declaration of query compoenents.

[2.0][DDC-183] Fixed issue with Annotations parser failing on identifiers that matches with token types.

[2.0] Incorporated CLI refactorings. Added support to namespaces and unlimited depth namespaces. Dropped globalArguments for now, since they interfer in DAG implementation.

[2.0][DDC-206] Fixed wrong enumeration value. Changed XSD location to point to the document on the website.

[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.