This includes a fix to the audio tours and a fix to trl-8 in the turtle chapter and a new picture for choice D

This includes a fix to the audio tours and a fix to trl-8 in the turtle chapter and a new picture for choice D

The fix for the audio tour was to remove the timer (interval) and use events instead.  I tested this in Safari, Chrome, and FireFox.  

The fix for trl-8 was to change the picture for choice D.  I also added better alt text for each of the choices.