[2.0] Changed structure of creation of SqlWalkers in DQL Parser. They are now strings instead of instances of dummy classes. Implemented nesting level check for ResultVariable

[2.0] InputParameter removed from Literal, since it's not actually a literal value. Changed grammar rules to accomodate this decouple

[2.0] Streamlined result structures. Hydration improvements: Small overall improvements, large improvement for (joined) fetched collections (~60%). 

[2.0] More work on DQL parser of Doctrine 2.0. More semantical checks included. Missing scope checking of ResultVariable (SELECT and Sub-SELECT differences). Removed invalid grammar rules.

[2.0] Implemented more TODO items in DQL Parser. Optimized PathExpression. Changed wrong grammar rule name in EBNF.

[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

[2.0] Refined implementation and semantics of the merge and detach operations. General cleanups and API improvements. Added a testcase for detaching/serializing->unserializing->modifying->merging to demonstrate the transparent serialization.

[2.0] Finished reorganization of grammar rules in DQL parser source code. Renamed some private methods.

[2.0] Accomodate joincolumn names in the metadata, in the selection and the hydration processes. Improved Api of the ProxyFactory. Working implementation of lazy loading for *-to-one associations (affects #2348)

[2.0] Changes in DQL grammar for optimization purposes. Implemented new DQL grammar rules and did a couple of TODOs

[2.0] Moved locking tests into Functional namespace. Fixed several missing flush() calls in some functional association tests. Reordered DELETE statements for ecommerce model tests in OrmFunctionalTestCase in order to maintain referential integrity. Fixed issue with bi-directional self-referencing one-one associations. Some other small improvements and cosmetics. Small hydration performance improvement through inlining method call in UnitOfWork::createEntity().