[2.0] Fixed some known issues with inheritance, especially class table inheritance, like join columns not being selected.

[2.0][DDC-49][DDC-50][DDC-33] Fixed DDC-49 and DDC-50. Also addressed DDC-33. Various other small changes and fixes. For problems with proxy objects please refer to the updated documentation.

[2.0] Refactored classloader architecture. Renamed ClassLoader => GlobalClassLoader. Introduced IsolatedClassLoader that is suitable for participating in autoload stacks. Added 2 example entity classes to the sandbox with 2 xml mappings and 2 yaml mappings. Simplified sandbox setup.

[2.0] Refactored pieces of QueryBuilder, it does not use string concatenation anymore. Splitted from into from and join, allowing update and delete DQLs to be correctly built. Added missing entry set. Removed Expr\Having because it was useless. Updated docs.

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

[2.0] More preparations to fix character casing issue. Reverted and completed ConditionalPrimary parsing and added more tests for this.

[2.0] Fixed issue with functions accepting subqueries. Implemented missing Expr\Join class. Added Expr::*join helper functions.

[2.0] Fixed several referential integrity issues. Fixed critical issue with inserts being run twice on postgresql/oracle. Added support for additional tree walkers that modify the AST prior to SQL construction and started to play with it in a testcase.

[2.0] completed implementation of lazy loading for Collections. Created debug helper class. Fixed default for orderBy clause to ASC

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

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

[2.0] Updated semantical error to display token and text close to the found error. Some cosmetics applied.

[2.0] Test coverage for OFFSET AND LIMIT sql generation for all platforms and Query class with setFirstResult() and setMaxResult()