More polymorphic Overloaded Plus

We added new methods to the class Plus, this time to cover all the
different cases.
i.e. Constant,Delta; Delta, Constant; Jumble, Constant... etc.
Optimizing the results of the Polymorphic Plus

We want to minimize the cost of the functions that we use. We know that
Constant's are cheaper than Deltas and Delta's are cheaper than
Jumble's. So, we try to minimize the most that we can.