New Galaxy Settings

We have some new* settings for galaxies.

These changes are to support New Galaxy: TeamSSv1.0, but can also be used for any standard galaxy or player-created custom galaxy going forward.

Setting Description
Disable Aid The ability to send and receive aid is removed.
Disable Market The Galactic Market does not exist.
Single Race All Empires are the same race.

* Disable Aid is actually an old setting that broke a long while back, but it has been fixed.