guile-gtk with gtk 2

[Kevin Ryde]

I've had a go at adapting guile-gtk to use gtk 2.  The changes aren't
too terrible, once getting past some fundamentals like glib and GValue
signal handlers.

I suppose (still, after all this time) guile-gnome is the future, but
I'm using guile-gtk so this is as much for myself as anything.  I
propose to make gtk 2 the head in the cvs and have a release as
guile-gtk 2.0.  The 1.2 bits can continue on a branch for bug fixes.