[pygtk] PyGtk Windows Build and Installers (again)

[John Stowers]

Hi All,

I have committed all the necessary work to make PyGtk/PyGObject
buildable on windows again (bug #589671). 

Windows installers will be built from the windows branch of the
respective libraries. The only difference between the windows branch and
master is the former has a few defs commented out that break the build.

I would appreciate any additional testing of this work. The plan is to
build some updated unstable installers soon, but more importantly,
everything is now in place to build and release working windows
installers at the same time, and corresponding to, the next stable PyGtk
and PyGObject releases.

John