P0-B3: Part 1167: Debugging, Improvements

I have spent some time modifying and refining the extents for the random generation system for earth-planets.

During testing, I noticed that earthlike planets were often far too steep, or had far too little or too much foliage and ground cover, for the game to be playable.

Earthlike planets need to be surviveable by the player with basic tools, and so I needed to refine the random extents to make this possible.

There is less randomness between earthlike worlds now, but the distribution of resources and the ease of traversing the planets without vehicles is a lot better balanced.

I have also fixed some more minor issues with the water, etc.