Found bug in character insertion.

The bug in the character insertion creates a loop in the linked list.
I've made a change to the GetTestReadout method that will give us the
choice of getting the tree branches in the data readout.
Updated code for telling me if the node is the Empty Node.

While looking through the tree for the insert process, I was two nodes
claiming to be the empty node. I've updated the property that tells me
if a node is empty.
Got the huffman tree going past the 3rd character. It now seems to break down at the 9th or 10th character of the test.