Generic positioning

[Murray Cumming <murrayc murrayc com>]

We now have a patch for generic positioning in goocanvas. This puts x,
y, width, and height properties on the GooCanvasItem base interface,
without changing the behavour of existing x, y, width and height
properties where they already exist on some items. So it's not an API
change - just an API addition or simplification.

This allows applications to move and resize items without special code
for each type of item. The generic-position-demo shows how this can be
useful.

This is simpler than working with transforms and, unlike transforms, it
does not also affect details such as rectangle borders or specified text
sizes.

I'd like this patch to be considered, please.
http://bugzilla.gnome.org/show_bug.cgi?id=555097

-- 
Murray Cumming
murrayc murrayc com
www.murrayc.com
www.openismus.com