Prehistoric Universe

Short snapshot, which doesn't add much content:

• The prehistoric sword had a texture improvement.
• 2 new plants, the Asteroxylon and the Tall, which appear in both types of swamps.
• The Diadectes now appear in the prehistoric plain biomes but with very low probability.

Tomorrow the "Plants and Herbivores" update will be officially released and everything seen in previous snapshots will be added.