[Graphics] Formalize bounding box

[John W. Eaton]

On  5-Feb-2008, Michael Goffioul wrote:

| src/ChangeLog
| 
| 2008-02-05  Michael Goffioul <michael.goffioul at gmail.com>
| 
|     * graphics.h.in (base_properties::get_boundingbox): New method.
|     (figure::properties::get_boundingbox): Overload method.
|     (axes::properties::get_boundingbox): Likewise.
|     * graphics.cc (figure::properties::get_boundingbox): Return a
|     left-to-right/top-to-bottom bounding box rectangle.
|     (axes::properties::get_boundingbox): Likewise. The internal
|     flag defines whether position or outerposition is used.
|     (axes::properties::update_camera): Remove backend access and
|     use the new axes bounding box.

I applied this patch and checked it in.

Thanks,

jwe