Helper Method extracted CraftInventoryCustom.java

The Issue:
In CraftInventoryCustom.java there were two methods that were basically the same except for a few parts.

Justification:
Helps increase readability and reduces some duplicate code.

Break Down:
I extracted the method from splitStack and so takes two int values. And put in an if statement right after the if statement checking if the stack is null asking if the second int value is Interger.MAX_VALUE; which i set the j for splitWihoutUpdate. When the if statement passes then it uses the if/else from splitWithoutUpdate else it uses the if/else from splitStack. Depending on which it ran it returns that ones results.