* Limit number of incoming connections
* Check Endpoint::Listener before checking num_open_connections.incoming
* Maintain at least 1-1/n portion of outgoing connections
* Remove use
* Default incoming_peers_factor to 2
* Use max_incoming_peers and max_outgoing peers to check whether connections should be dropped
* Fix expected_max_peers: reserved peers are not counted in config.max_peers
* typo: fix test