Refactored components and began defining basic Entities and Systems. * Moved the components from parpg.objects.components into their own top-level package, components, and separated them into individual modules. * Added a few new components, including Behavior, Container and Containable. * Created the systems top-level package for defining Grease Systems and added stub classes for the ScriptingSystem and GameRulesSystem. * Created the entities top-level package for defining Grease Entities and added an incomplete definition of the Character entity type.