[Cairo] format for api docs

[Thomas Hunger]

Hi,
I did this during luchbreak (students have long breaks...):
http://www.iqo.uni-hannover.de/gnome/cairo/
its a rough draft. looks like i need to learn docbook.
Tom

p.s. gtk-doc tools do not like the two cairo_status_t enums with the same name 
in cairoint.h and cairo.h, it would need a little hack to make it work for 
cairo.

> It might work to put the documentation in with the most popular
> implementation (probably the XRender one). But I do agree this may not work
> well for cairo since the function names there are not the same as the
> public interface ones.