[2.0] Some Annotations parser docblocks, optimizations, etc. Fixed wrong syntax error token report in DQL parser

[2.0] Fixed warning in semantical error reporting (strpos with length over dql length). Fixed wrong grammar rule. Fixed wrong token position on semantical error reporting. Added more semantical checks in UpdateItem

[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.