- adding back .png file because PDF cannot include and build SVG files. Also renamed images to use a 'imagename.*' wildcard so that the correct format is chosen. See http://stackoverflow.com/questions/6473660/using-sphinx-docs-how-can-i-specify-png-image-formats-for-html-builds-and-pdf-im
Merge pull request #1500 from stevepiercy/master

- adding back .png file because PDF cannot include and build SVG files. ...