Creating Teacher Poll slide and isolating Teacher Slideshow constructor
Creating Attendee Poll slide and  Attendee Code Slide,isolating Attendee Slideshow constructor
Creating Blackboard Poll slide and blackboard Code Slide,isolating Blackboard Slideshow constructor
extracting initEvents, initSlides, initCurrentSlidePosition in slideshow
Resource url as properties for each xxCodeSlide
introducing getExecutionContextAtAndExecuteCodeAt method in CodeSlide
Moving author refresh special case to _update
using getExecutionContextAtAndExecuteCodeAt in TeacherCodeSlide
Removing the slideshowType method in Code Slide