Features in Games
For AI development it is useful to watch the AIs play. This patch adds a
new local human spectator player controller which does not have any
planets and does not count as active player.
In case all selected player controllers are spectators, or only one
non-spectating player controller is set, consider the match as
spectator-only and reject it as there is either no winner at all, or the
winner is known already (the only non-spectating player).