Make it a generic ADT

As an intermediate step toward the grade-sheet sorter, we're going to make a generic version of Heap and test it using a simple integer Sorter.

1.

Copy the Comparable class definition from the Priority Queue assignment. We're going to adapt Heap to work with Comparable items and create a simple class that is a member of the Comparable abstract class.

2.

Make a new class named HeapItem with a single integer as an instance variable. It should implement Comparable (and provide methods named compareTo and toString). See PQItem for an example of how to do this.

3.

Compile and run the three class definitions so that they work again, generating 100 random numbers, inserting them into the Heap, then removing and printing them.