* Cover letter

Having a single header file for all autocleanups definitions was a
reasonable stop-gap measure, but now GTK+ is starting to use G_DECLARE_*
macros. This means that every class using a G_DECLARE_* macro will need
to include "gtk.h" to avoid compiler warnings, which is not acceptable.

By moving the G_DEFINE_AUTO* use to the header that defines the type we
allow using the G_DECLARE_* macros without sacrificing the ability to
include only the needed files when deriving from a class.

* Commit

This commit changes all includes relative to GtkWindow to define their
own autocleanup macros.