Ping times should be displayed in server list

[andy5995]

In the game lobby where the list of servers is displayed, each server should show the ping time from the client.

ping every 15 seconds and show the ms of the last ping, and also show the average ping time of all pings sent.

Those 2 numbers could be shown below the server line, so we don't have to add extra info to the server line.

then a blank line underneath, to separate it from the server that follows. Or maybe use some graphic as a separator instead of a blank line.