DnD of Contacts one on another to link it

[Erick Pérez Castellanos <erick red gmail com>]

Hi:

Afte some talk with Allan, Alex and some others we got this idea, we can
allow people to link contacts by dragging one contact over the other.
the dragged will be linked into the other one, or that what I think.

Well, I got the patches working, there's two think still bothering me:
1. Which icon/image/cairo_surface will we use on the DnD to tell we are
linking a contact ?

2. I have to be online to handle my contacts ? I tried create a new
contact being offline at home and I got some error. Is this right, or is
this a bug ? I think uses should be able to handle their contacts no
matter their connection status. Anyway that can be a bug.