Co-op campaign matches and command markers: mission relay, allied masters, temporary flags

lang/en.lang

@@ -619,6 +619,8 @@ net.error = {0}
 net.rooms = Open matches
 net.no_rooms = No open matches.
 net.create = Create match
+net.coop_mission = Co-op campaign: mission {0} ({1})
+net.coop_create = Co-op campaign
 net.join = Join
 net.join_hint = Match code
 net.seats = Seats