Peer discovery broken about alvalor-go HOT 1 CLOSED

I fixed this with 27b11e2e8f38ef0e81b7f3560b38b4f7a490ee07.

I noticed that actually, there was never any address shared, as nobody was adding peer addresses to their address book.

Now, a peer will share his own address right after successfully establishing a connection, but only if he is listening. Then, he will add the peer addresses he receives to the address book. Meaning that we only share addresses of listening peers over the network.

This might not be optimal yet, because addresses are only spread through the network after a peer doesn't have the desired number of peers and requests them. This might be rather slow for the propagation. We should run some tests on that.

from alvalor-go.