GDK wrappers in gtkmm-1.3

I just finished converting the GDK wrappers in gtkmm-1.3 to auto-generated GObject-based classes, which has
simplified the gdkmm memory model a lot.

We’re using a smart pointer that refs the GObject
automatically, and I was pleased to find that, with a
templated copy-constructor, it’s possible to use the smart
pointers polymorphically just like the underlying C++

This is consuming a lot of time. I need to get it done
and start looking for some paying work.