[DBAL-2958] Replaced extension of \PDOStatement with a composition to avoid having to replicate the \PDOStatement interface in ResultStatement

Other drivers (including the cache) never supported fetch modes that are
not listed in `FetchMode`. Converting between the contants is only done
for PDO, so BC only needs to be restored here. PDO will validate the
fetch mode, we don’t have to.

HHVM does not allow declaration of interface implementation without
real implementation of methods which parameters differs from parent
class.

- 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

This enables a more natural way of interacting with result sets,
and re-introduces in Doctrine DBAL a feature that has been available
in PDO from the begining.

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