Broken build

[Joe Shaw <joe helixcode com>]

Since bonobo-embeddable-factory.h was removed from bonobo.h,
bonobo/samples/compound-doc/bonobo-hello/bonobo-hello.c and
bonobo/samples/compound-doc/sample-canvas-item.c stopped building. For the
time being, I added an #include of those into the sources, but they should
be ported to use BonoboGenericFactory instead of BonoboEmbeddableFactory;
I just don't have the time right now to do it. I'll do it later this
afternoon if someone doesn't beat me to it first.

Joe