client-side-windows merged

[Alexander Larsson <alexl redhat com>]

The client-side-windows branch has now been merged into master. 

The current state of this code is pretty good. There are two known
regressions on X11 (see http://live.gnome.org/GTK%2B/ClientSideWindows),
but both are corner cases. The quartz backend is supposed to be at least
as good as the old one. The win32 backend is in pretty bad shape, but
after some hacking today it at least builds and mostly works.

I will continue working on this code, fixing regressions and getting the
win32 backend up to speed. However, at this point we need broader
testing, and doing that work in master will help us get that.