UP-Engine: Added missing methods to UPAreaProxy.
UP-Engine: Removed unnecessary includes.
UP-Engine: Removed getCurrentMap() since known or visible map areas depend on selected characters.
UP-Engine: Created the UPCharacter class.
UP-Engine: Created the UPNotificationsObserverInterface class.
UP-Engine: Removed notifications observer which seemed a bad way to implement observers.
UP-Engine: Removed notifications observer which seemed a bad way to implement observers (forgotten stuff removed as well).