SPECIAL FEATURES

1. I used scaleX = -1; to point the arrow button to the left
2. A mouse event was used with two if-else statements (in a buttonClick function),
   one for the left button and one for the right button. The buttonClick function causes
   the images to display in sets of four thumbnails and one large image. The buttons advance
   (right button) or go back (left button) in multiples of 4 starting at 0 for the first image.
   Four new images are displayed each time the buttons are clicked. The large images that
   display are numbered 0,4,8,12, and 16. Clicking on thumbnails causes them to display larger.