Authentication support

[arthuro555]

Not everyone is supposed to be authorized to access all scenes. Some games can contain confidential information, and should not be synchronized with a client before authorization has been ensured for them. THNK would provide a function to listen for connection request. By default, they are accepted, but they can be marked as delayed or refused. Delaying them can be useful for asynchronous operations, like checking on a database for user permissions. Only once accepted will the user trigger the "Connected" event and be sent a snapshot of the scene.