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.
You should not use `cFastRandom` for generating, because it's not repeatable. If someone regenerates the chunk, the result will be different from the first generation. Use `m_Noise` instead to get the random value (`(IntNoise2DInt(chunkX, chunkZ) / 7) % 100`)