Numerous additions, deletion

-EntitiesLayer uses string to group sprites instead of Sprites Enum
-EntitiesLayer now controls Camera object
-Removed partially finished code for Sprite animation
-PlayerManager and NPCManager removed for loss of abstraction
-Removed Human and Zombie classes
-Removed LuaEngine, PluginManager will replace it's functions
-CoreEngine now has plugin support
-Added PluginManager
-Added PluginComponent
-Removed SaveManager(another will be created to replace)