Peer list refactoring

- Remove peers that weren't seen for > 1 hour
- Better peer selection algorithm for PEER_LIST_RESPONSE

src/p2p_server.h

@@ -169,6 +169,7 @@ private:
 		raw_ip m_addr;
 		int m_port;
 		uint32_t m_numFailedConnections;
+		time_t m_lastSeen;
 	};
 
 	std::vector<Peer> m_peerList;