message: Require at least three participants for a congress
diff: @@ -531,6 +531,12 @@ class Congress:
  else:
  iHostPlayer = utils.getRandomEntry([iInvitee for iInvitee in self.lInvites if gc.getPlayer(iInvitee).getNumCities() > 0])
  + # normal congresses during war time may be too small because all civilisations are tied up in global wars
  + if len(self.lInvites) < 3:
  + data.iCongressTurns /= 2
  + data.currentCongress = None
  + return
  +
  # establish contact between all participants
  for iThisPlayer in self.lInvites:
  for iThatPlayer in self.lInvites:
  