Use lambdas instead of references to managers (refactoring)

[the-argus]

Currently, in order to create things in the game, we pass a reference to the manager for the target object, and then use some function like Manager.CreateObject(args). Instead, pass in an anonymous function that is a passthrough for CreateObject.

Example of old/bad format: passing in a reference to the bulletManager to a new EnemyManager, just so we can call bulletManager.FireBatch. Just pass in a lambda to FireBatch instead.

Example of new/good format: The player is instantiated with an action delegate which it then uses to create bullets.