[2.0] Refactored SQL query building process and hydration. Hydration should now support result sets with any number of root components. Introducing ResultSetMapping that is used by hydration instead of queryComponents. This allows mapping of arbitrary SQL queries (NativeQuery).

[2.0] Parser work. Added double-dispatch functionality to AST node classes for use in the SqlWalker to reduce big if/else instanceof checks and for better maintainability. Also its less error-prone in the SqlWalker because its harder to miss a conditional case. Added new extensible DQL function implementation.

[2.0] Parser work. Drafted logic for multi-table deletes through DQL (for Class/Concrete Table Inheritance)