v3.4

Issue list: https://github.com/mnapoli/PHP-DI/issues?milestone=10&page=1&state=open

- [x] Deprecate XML definitions
- [x] Allow indexed non-empty arrays being valid parameter values (unkind)
- [x] Make ContainerBuilder fluent (drdamour)
- [x] [Test lazy injection for constructor injection](https://github.com/mnapoli/PHP-DI/issues/100)
- [x] [Handle optional parameters for constructor/method injection](https://github.com/mnapoli/PHP-DI/pull/101)
- [x] Revert #108
- [x] Change log
- [x] News entry