Also:
* Convert main.css to less because I can't figure out how to do svgs
and fallbacks by hand
* Add gradient image to fit with book for really, really, really wide
displays (and move book background to globalWrapper to make it
actually work)
Change-Id: Ie6f5b6b87b475953274688fc4640f9fa17184fa4
Also delete unused images, since even if something is
somewhere using them anyway (looked, couldn't find
anything), it wouldn't be able to find them in the new
image location regardless.
Wiki.png, magnify, and link are all part of core and have
been for some time.
Change-Id: Id7a02155a5f1b207908c9c0c8f7519b6d3f9a886
