-Added an initilization check to XmlLoader.
-Added a persistence option to entities.
-Fixed typo in Persistent.
-Added persistence to the entity tool.
-Added a door class.
-Added basic door support to entities that can't use doors.
-Added options to the entity tool to allow entities to use doors or not.
-Updated Map with persistence options.
-Fixed an oversight in IsPersistent in Map
-Fixed yet another typo of Persistent.
-Added a transition class.
-Added world class.
-Added IsPlayer() to Entity.
-Fixed glitches in a couple of components.
-Added code for moving between doors.
-Added a reference to a map's world in map.
-Added an update function to World.
-Fixed error in MainForm.
-Fixed error in extension method ToXnaEntity().
-Fixed some calls in Entity.