Developing basic item artifacts

Since that all item classes are uncoupled through the factory design. User can personalize the artifacts (node, links, groups, decorators, controllers and default renderers) implementation. In case of a specific use, the user can change the rendering, inheritance and implementation. For this he should refers to the IFactory.addOrReplaceClassReference. For example, to speed the display operation ( since that UIcomponent are more heavy than sprite), user can switch from UIcomponent version to sprite one by only replacing classes in the factory through this statement. visualizer.itemFactory.addOrReplaceClassReference("sprite",LightGenericSprite)