Animal terrain finisher

Adds animals to cChunkDesc entity list on chunk generation.

resolves #1595 

Note: animals do not spawn, either the list does not get refreshed and sent to world, or the mobs spawn too far away and are removed shortly after.
This will generate the same coords - `x == z`. Add a constant to the coords so that the input to `IntNoise2DInt` is different for each coord.