(incompatible) gnome-app-helper changes

[Elliot Lee <sopwith circ us eu org>]

- Supports stock icons (for toolbars) and menu items (for menus).
- Automatic internationalization.
- One structure to use for both toolbars & menus (Thanks to Chris Toshok
  for idea & design). Doesn't do nested toolbars yet. Cope or code. :)
- Support for accelerator keys (totally untested)
- The gnome_app_create*() functions have _interp() variants to allow
  greater flexibility in callbacks.
- There's more. I'm sure someone will discover new bug^H^H^Hfeatures.

Much remains untested, but the all of the games' menus work with the new
GnomeUIInfo setup, so something must be right ;-) Hopefully this should be
the last incompatible change in a long time, but please yell (quickly) if
you see anything else that needs adding.

If you have any questions at all about using this, please ask!
-- Elliot
Will read UCE for food! Charge of only $500 per message received. ;-)