Most of the refactoring issues we are seeing are probably due to the fact that we are trying to manipulate a ScenePlugin out of a Scene (the GameManager is not a Scene and holds a reference to a ScenePlugin coming from a Scene that might get invalidated by Phaser 3).
Furthermore, if we want in the future to be able to scale, scenes could be hosted on different servers. Therefore, it makes no sense to have one connexion for the whole application.
Instead, we should have one connexion for each scene.
Taking what was done in the LoginScene regarding character selection and putting it in its own scene.
Also, making character selection possible via the keyboard.
