Connection : fix bug when node with several clips.

The fixed bug happened when we tried to delete a connection between node with several clips. Depend on the situation, we did not delete the right connection in tuttle ! Now it's fixed.

Also improve display of connections (on terminal, for debugging).
Connection : fix bug in updateConnectionsCoord.

The fixed bug happened when we had at least one connection in the graph, and we created a node (whatever the type). The wrapper layer was not up to date for a moment, and we tried to access to the node wrapper, which did not exist (yet).