Now that we support more than 2 clients per shared buffer, we can use them
for window icons. I didn't do that previously since it would have made the
Taskbar process unable to access the icons.
This opens up some nice possibilities for programmatically generated icons.
This behavior and API was extremely counter-intuitive since our default
behavior was for applications to never exit after you close all of their
windows.
Now that we exit the event loop by default when the very last GWindow is
deleted, we don't have to worry about this.
Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.
This avoids building the code twice, and will encourage better separation
of concerns. :^)
