Galaxy setting for planet limit is working for exploration

For context, see Mathano 3 Cataclysm.

This is a partial fix to address the immediate issue in Manthano where players were able to explore more than the intended 99 planets.

There is follow-up work needed:

  1. This fix is not retroactive; we still need a way to reduce size for players that are currently over the limit. Those players should however no longer be able to explore further.

  2. This fix only applies to exploration; a related fix will be needed for attacking if we want to use this setting in other galaxies/rounds. This is not a problem for Manthano specifically as it is a peaceful galaxy.

  3. This limit itself is a workaround to a more complex problem. We eventually want a means for new players to gain planets even in an otherwise full galaxy. We need mid-round system and planet creation for this.

The items above have been added to our backlog but haven’t yet been prioritized and do not currently have an ETA.

Thank you @Rawrr for helping me test this.