Hi Guix,

attached are patches to add IBus.  This was a bit difficult to package
because I discovered two things rather late:

- our gtk+-2 package doesn't install its typelib file (see
  http://lists.gnu.org/archive/html/guix-devel/2015-03/msg00456.html)
  
- the python2-pygobject-2 package is not the python2 equivalent of
  python-pygobject.

The home page for python-pygobject was set to the home page of the
pygobject 2.x bindings, although the API of the 3.x series differs from
that of the 2.x series.  This is fixed in the first commit.

The second commit adds Python 2 bindings for the 3.x series (previously
we only had Python 2 bindings for 2.x and Python 3 bindings for 3.x).

The third commit adds IBus itself.  Since the glib-or-gtk-build-system
already wraps the ibus-setup executable I decided to patch the wrapped
executable rather than adding another layer of wrapping.  This is why
the "wrap-with-additional-paths" phase looks pretty ugly.

Please note that this might fail with a runtime error unless our gtk+-2
package is fixed as shown in
http://lists.gnu.org/archive/html/guix-devel/2015-03/msg00456.html

~~ Ricardo