* Change packages order alphabetically
* Add PHP-DI package to Composer template
* Remove ContainerInterface from APIs
User shouldn't access container directly, it's an anti-pattern.
Ref: https://php-di.org/doc/best-practices.html#rules-for-using-a-container-and-dependency-injection
* Change app templates to use PHP-DI
Application looks more like a default Slim skeleton now.
Ref: https://github.com/slimphp/Slim-Skeleton
* Rename SlimRouter to RegisterRoutes
Since it's callable class new name fits better.
* Add short documentation
* Refresh samples
