Speakers: update images.
Speakers: add a naive slideshow implementation.
Slideshow: genericize the slideshow script as slideshow.js.
Slideshow: defer loading until images are loaded.
Slideshow: allow changing of images via swiping.
Slideshow: fix bug where swiping interrupts scrolling on iPads.
Slideshow: add some iOS-style friction when scrolling out of bounds.
Slideshow: prevent accidentally dragging the image when swiping during animations.
Slideshow: rename it 'swipeshow'.
Slideshow: enable hardware acceleration on an iPad.