Agent: change the trait
Agent: change the trait

As the Ports sturct is removed, the interface for the Agent must change. So the
`Agent` must manage the ports directly : connection, add element in array,
disconnect, ...

All the disconnecting part are not yet implemented.

fractalide/fractalide,dmichiels/fractalide,fractalide/fractalide,dmichiels/fractalide,sjmackenzie/fractalide,sjmackenzie/fractalide,fractalide/fractalide,dmichiels/fractalide,sjmackenzie/fractalide