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.
Still not good here. The `PackCenterX` and `PackCenterZ` should use the `Tries` variable as well, and `OffsetX` and `OffsetZ` should use both `Tries` and `i`.