[DBAL-2546] Fixed the failure of `Functional\StatementTest::testReuseStatementWithParameterBoundByReference()` on ibm_db2

- Fixed docblocks
- Removed return statements on void methods
- Cleaned up unused private / local variables
- Fixed license issues
- Removed SVN leftovers
- Fixed doctrine-project.org links
- Added line breaks before return statements

Fixed pecl/ibm_db2 Driver and Connection to run smoothly against the complete test-suite (depending on a c-patch to the extension though)

[2.0][DDC-354][DDC-425] Fixed. Encapsulated SQL logging better in the DBAL. Added binding types to DBAL mapping types as well as using these binding types in the persisters. Query and NativeQuery now support PDO binding types as well as DBAL mapping types when binding parameters.

[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.

[2.0] Moved code between Query and AbstractQuery. Added first NativeQuery implementation. Hydration work and code movements for discriminator column usage. Started implementing Single Table Inheritance.