Refactor Actors class
By design, an Actors class is a storage, which allows to map object pointers to CharacterControllers and do a high-level handling for character controllers.
But for some reason the class itself started to do many different actors-related things, which are not related to actors list at all. Many fuctions accept MWWorld::Ptr an only argument (such as adjustMagicEffects(), calculateDynamicStats(), updateMovementSpeed(), etc). Such functions can be moved to the Actor class or to separate files.