This commit implements average RTT estimation based on PING-PONG between active TCP connections.

Average RTT can be used to update edge weight and propagate it to the network.
tinc dump edges has been also extended to give the current RTT.
New edge weight will change only if the config has EdgeUpdateInterval set to other value than 0.

- Ignore local configuration for editors
- Extended manpage with informations about EdgeUpdateInterval
- Added clone_edge and fixed potential segfault when b->from not defined
- Compute avg_rtt based on the time values we got back in PONG
- Add avg_rtt on dump edge
- Send current time on PING and return it on PONG
- Changed last_ping_time to struct timeval
- Extended edge_t with avg_rtt

src/connection.h

@@ -99,7 +99,7 @@ typedef struct connection_t {
 	int tcplen;                     /* length of incoming TCPpacket */
 	int allow_request;              /* defined if there's only one request possible */
 
-	time_t last_ping_time;          /* last time we saw some activity from the other end or pinged them */
+	struct timeval last_ping_time;          /* last time we saw some activity from the other end or pinged them */
 
 	splay_tree_t *config_tree;      /* Pointer to configuration tree belonging to him */
 } connection_t;