Threateningly mobs

Change:

• snailacid block will remove self now.
• flamehorn eat hay block now.
• inferno have new texture.
• bettle great sword can craft now, and new texture.
• change some value.

add:

• Added mob kill achievement.
• Added unique item for heavymobs(No functionality currently).
• inferno can shoot projectiles now.

new mob: Regalhart (heavy)

• a huge deer.
• spawn in forest taiga...etc.
• When its HP drops to a certain threshold, it will activate its special ability.
• Use ability only once.