Minecraft swamp update

Adds different tree types to live among the oak and mangroves, Firefly upgrade, two new mobs the alligator (crocodile as savanna variant) and the platypus. The alligator gives a new challenge to the swamp and savanna, drops alligator scute when killed. When a scute is put with a shield in an anvil it gives it a cool texture with extra durability. The platypus is a passive mob that eats tadpoles, when tamed it retrieves alligator teeth which can be used to craft a tooth spear that deals heavy damage. Feel free to change anything I mentioned about the swamp update.