[2.0] Changed identifier quoting strategy to something simpler. Dropped Doctrine prefix from annotations.

[2.0] More general work on the SchemaManager and Platform classes. Making API more complete and adding sqlite and mysql test coverage.

[2.0] Fixes and enhancements to sequence generators. Test suite now runs & passes against postgres. Other minor, unrelated cleanups.

Started refactoring in DQL parser to separate Production into Parser and AST classes.
Finished first tests. Currently only 4 are active in IdentifierRecognitionTest, and only 2 are passing.

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reverting the reorganization done in 3455-3456 in order to make merging my experimental branch to trunk easier.

Preparation for new organization of code in to sub packages. Changed autoload() to work with new structure.