Got rid of Colormap, added cairo stuff, refactoring

Colormap -> Visual
    I was able to remove some binding code

Pixmap -> Cairo ImageSurface
    I started this work, but lots to do

OnEventExposed -> OnDrawn
    Started replacing all of these.

Also, commented out some code with the comment:
// GTK3

This is a smaller commit so that David's iPad browser
can handle view it without being too slow