Image sizing update in Reveal slideshows

[Andrew Scholer]

A quick warning to anyone using the Reveal output to generate slides with images.

The Reveal output now has CSS to scale images to fit the container (side by side panel) they are in. This eliminates some sizing issues and brings the behavior in line with image sizing in "regular" HTML output.

This represents a change in behavior that may affect existing slideshows which contain a small image in a large side by side panel. If those image are now undesirably large, you can reduce the size of their containing panel.