include initialization_versions.sgml, file-saving.sgml and

include initialization_versions.sgml, file-saving.sgml and

        * gdk-pixbuf/gdk-pixbuf.sgml: include initialization_versions.sgml,
        file-saving.sgml and module_interface.sgml.

        * gdk-pixbuf/tmpl/module_interface.sgml: add short description.

        * gtk/tmpl/gtkarg.sgml, gtk/tmpl/gtkdata.sgml,
        gtk/tmpl/gtkcellrenderertextpixbuf.sgml: removed, since they described
        no longer existent stuff and aren't included anymore.

        * gdk/tmpl/color_contexts.sgml, gdk/tmpl/input_contexts.sgml,
        gdk/tmpl/input_methods.sgml: removed, since they described no longer
        existent stuff and aren't included anymore.