Added a method for finding the node to switch with that will help restore tree balance.
Removed a method from the HuffmanTree class the isn't needed.

When I started writing this class, I though it would be a handy method
to have. In hindsight, each reason I had though of for having it, has
proven to be either wrong or un-needed.
Finished methods for balancing the huffman tree.
Removed method stub that wasn't needed after all.