Original Behaviour was using old methods for detecting entering/exiting universe,
they are now all under the same hood and the original is kept for UniverseEntranceManager
because it needs to enter the universe without itself. The internal behaviour kept under
a subnamespace of "Core.Internal" for the purpose that it might come in handy for other use cases.
All delegate events are refactored to use the Event<TSender> and Event<TSender, TArgument> for performance issues regarding delegate events creating garbage, also this gives us better control on event invocation since C# Delegates did also create unnecessary garbage during Delegate.DynamicInvoke
