Expect large scale breakage

[Jody Goldberg <jody gnome org>]

I've committed the first pass at porting to some of the new toys in
gtk-2.3.  Expect the ui to be somewhat broken as the various pieces
get fixed and the tree moves around in preparation for the goffice
split.

WARNINGS

1) The ui only works from within the dir gnumeric/src right now.
   When we have a plan for where to put the file it will be fixed

2) None of the custom combos work very well.  We'll get to them
   shortly.  If you're interested in helping out please send a note
   to the list to avoid conflicts.

Why are we doing this ?
    The new api gives us the chance to make the last dependency on
    bonobo and libgnome* optional.  A few more small cleanups and a
    gtk only build (aka win32 land) will be ready.

    It also gives us enough power to really support user editing of
    the menus/toolbars/accelerators and proper support for plugins
    to extend the ui.