PATCH: libgnome bugs

[Richard Hestilow <hestilow ximian com>]

I found these while hacking default-applications-properties. I also
modified libgnome.schemas to be more in line with what
default-applications-properties, and removed the UI options to be moved
to libgnomeui.schemas. Patches to libgnomeui and gnome-core's
"gnome-edit" (which has yet to be ported to gconf) will follow, to
reflect these changes.

Okay to commit?

-- Richard