Fix compatibility with Moon Overhaul

It changes how the ocean(surface) layer generates. Many people seemed bothered by the way it was. In some cases this will result in a less deep ocean than you had before. Now ocean depth will vary depending on planet size instead of being strictly defined.

This will only affect planets generated after the fix went into effect.

Have a variable gravity now, just like any satellite. The gravity of any satellite body won't ever be terribly high. It doesn't make sense they'd have a set gravity just because it had a different biome.

And I refer to vanilla moons, not any moon types added by FU. I haven't really touched those.