Merging graphics branch

[John W. Eaton]

On 18-Jun-2008, Michael Goffioul wrote:

| Actually, Matlab supports both. Value classes are what is currently
| present in octave. Handle classes are somehow a generalization of
| what the current graphics system implements, where objects act
| more like pointers.

OK, so should we be thinking about ways to implement the handle graphics
system as these new kinds of objects?  If so, then I think that is a
relatively big project.  I know that I don't have time at the moment
to think about how this should be done.

jwe