Vampire (Vampirism)

The vampires are creatures that spawn naturally,like the zombies on the night.If they bite you,they might infect you with effect: sanguinare vampiris,after a minecraft day,you will turn into a vampire,if you die,you will lose the effect,ignoring keep inventory.The vampires also can spawn in the biome,vampire forest.They might drop his teeth,that the player can use alternatively to turn himself into a vampire without being bitten by one.