Code review comment for lp:~gaspa/a4/presentation-objects

now bugs should be fixed.

Re-writing down what this branch aims to do: implement a (still stub) system to handle graphics objects, both simple as rects/circles and more complex as the image or "polaroid" object.

What comes toghether with these changes:
 * a method in region.py that helps calculate point coordinates between screen coords and svg coords.
 * I added a sample of the polaroid object, perhaps we could keep them in that directory (I'd like to have more 'complex objects' than simple ones, that can be drawn simply by a normal svg editor)
 * there is a couple of unused button in the editor toolbar (things like 'frames','notes') that could be drop... perhaps :p

If someone can do a little test if everything seems to work, I'd merge this to trunk in the next days.