Add StepNode class & LinkedList

Created a StepNode class for our LinkedList. The StepNode contains the
positionalData array, threshold, and stepCount for a given Window. Each
StepNode essentially represents one of our Windows.

I was also working on an IO stream method before the LinkedList
implementation. We could slightly modify the IO stream method to output
our LinkedList to a text file.  Both could be used for debugging
purposes.

One thing I realized is that stepCount is an aggregate number. If we
wanted to have a unique step count for each window, would have to add a
new variable. StepCount might not even be needed as a StepNode
attribute.
Quick LinkedList Fix

I had added a new node to the LinkedList in the wrong place. Fixed now.