Changed Milk, added more functionality cowmilker

Changed Milk to LiquidStack only and registered it in LiquidDictionary.
Cow Milker now scanning for Cows and adding 10 milk each 5 seconds.
Multiple cows have no effect. Scan range can be upgraded in the future
with RangeUpgrades. Cow Milker GUI draws a proper white rectangle for
the milk stored in the cow milker.