event watchers can be stopped
begun refactoring stateQueryService to interface inline with actual expressions
continuing to align contextExpression interfaces around watch and evaluate + events
improving destinction between event and state expressions by removing generic method which creates either
minor refactoring and slight change to eventExpression interface to use 'on' mehtod rather than onTriggered
created stateQueryService
preparing to migrate states to using new context expressions by making it possible to add states to the state engine after construction