Add SlotPotionBottle for diff visibility
Override b(EntityHuman entityhuman, int i). Fixes BUKKIT-1929

CraftContainer does not override b(EntityHuman entityhuman, int i). Without overriding this method, "shift copying" will not work properly, and can cause a stack overflow and crash the server. This commit fixes this issue by properly overriding b(EntityHuman entityhuman, int i) and switching the process according to the inventory type.