Autogeneration changes

[Owen Taylor <otaylor redhat com>]

As a last minute cleanup before 2.0.0, I've made some changes to 
the way libgtk registers types; this doesn't change the API at
all, though it changes the set of exported symbols quite a bit.

 - I've switched over all the GTK_TYPE_FOO variables for enums
   and boxed types over to get_type() functions

 - I've gotten rid of the use of custom awk scripts and some of
   more unusual complexities in gtk+/gtk/Makefile.am

I think I've made all the necessary changes to gtk.def to track this
(and added one or two missing entries along the way).

I didn't touch makefile.msc and makefile.mingw, so they probably need
some updating.

Regards,
                                        Owen