This changes README.md and the comment for RedBlackNode to more clearly explain what the project is all about. It emphasizes the fact that RedBlackNode provides public access to the tree's structure. It changes the usage example in README.md from a short RedBlackNode subclass highlighting how easy augmentation is to a medium-length pair of tree and node classes that show how to use insertion, removal, and augmentation.
This change also makes minor improvements to comments for RedBlackNode methods.
