[2.0] Work on CLI: Added SchemaToolTask with preliminary support for dropping/creating the database schema. Prepared the sandbox. Adjusted build to include the sandbox.

[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] Implemented DQL bulk DELETE support for Class Table Inheritance. Other cleanups, refactorings and docblock additions.