Add 'recent players' info message

[Kaffeine]

On a player joined an empty server print a message: "Players left the server N minutes/hours ago".
If a last player left the server less than 2 minutes ago print "... left the server a minute ago".
If minutes >= 60 then print a rounded number of hours.
E.g. for 60 and 89 minutes say "an hour ago", for 90 to 149 minutes say "2 hours ago", for 150 to 209 say "3 hours ago", etc.

Track the last TWO players to still inform the last joined/rejoined player about the other player time. Probably use the player name to distinguish players.