fix column default value lifecycle
[DBAL-722] Introduce subclasses for runtime relevant exceptions (NotNull, DuplicateKey, ForeignKey Constraint Violation).
fix documentation
[DBAL-722] Add missing doc @return.
Merge pull request #459 from deeky666/DBAL-544

[DBAL-544] Fix reference to legacy Query::HYDRATE_* constants in ResultStatement documentation
[DBAL-722] add @since tag [ci skip]
Merge pull request #458 from doctrine/DBAL-722

[DBAL-722] Introduce subclasses for runtime relevant exceptions
[DBAL-139] Add support for creating sequences with CACHE/NOCACHE options.
Merge pull request #456 from deeky666/DBAL-44

[DBAL-44] Fix column default value lifecycle