CSS background colors and images

Adds support for background colors and Images (only for block elements)

 - CSS attributes background, background-image, background-color, background-repeat, background-position (works for pixel values)
 - Experimental support for CSS height and width attributes for block elements. Useful to display elements that have no contents but only Background

The Google result page contains images now - they are contained in a single sprite image, which unfortunately results in some glitches I couldn't fix.
This method is not needed if it only calls its super method.