[gtkada] GtkFileChooser

[jeff at thecreems.com]

This widget (and its associated family of widges) has been 
in Gtk for nearly a year now. While not perfect it 
certainly is a big improvement over GtkFileSelection.

I've played around with the generate.pl script a bit on 
these files it appears that getting these things bound 
means solving a few different issues (from variadic calls 
to a few addition types that don't fall directly into the 
OO hierarchy).

In any case it probably is doable. Has anyone on the list 
started/finished this on their own and just not 
contributed back yet?