This lets different things dynamically create the services they need,
and sorts out the horrible hacks that view1090 used to make outgoing
connections. Now you can explicitly create a service and tell it to make
an outgoing connection.
This means that view1090 can now just set all the ports to zero (to disable
the listeners), do a normal net init, then explicitly construct the beast
input service without a listener and tell it to make a connection as needed.
