V3.0

Version 3.0

Issues: [Issue list](https://github.com/mnapoli/PHP-DI/issues?milestone=5&state=open)

* Configuration is reworked from scratch with different backends
* Provided [configuration backends](https://github.com/mnapoli/PHP-DI/blob/3.0/doc/definition.md):
    * Reflection
    * Annotations: `@Inject`, `@Injectable`
    * PHP arrays
* As a consequence, annotations are not mandatory anymore, all functionalities can be used with or without annotations.
* Setter injection
* Constructor injection
* Scopes: singleton (share the same instance of the class) or prototype (create a new instance each time it is fetched). Defined at class level.
* Code now follows PSR1 and PSR2 coding styles
* More tests
* ...