Barrel Logic Rewrite

I have rewritten how fluids transfer in and out of barrels. There is a
small bug of how items are placed in your inventory after filling them
from a barrel, but the logic seems to work. Empty barrels also now fill
with water when it rains. Still have to check to make sure that they
don't fill in snowy biomes.
Barrel Rain Filling Fix

Fixed the barrels so that they would not fill with water while raining
if they are covered by a  block.