No More Player

Okay, this isn't the flashiest update. I spent most of the weekend making major changes to the internal infrastructure of the engine. The most major of these changes was removing the Player class which was previously used to represent the state, position, and current animation of...well, the player.

All of these features and more are supported by the Entity system, so I converted all instances of player logic to instead use an entity. The end result was the deletion of a bunch of code that wasn't needed anymore because the features were already supported by the Entity system.

I also changed a bunch of stuff with how the scripting infrastructure is organized and edited through the level editor, but it's not worth showing yet.