Some javadoc stuff and simplification of Review class hierarchy.

ReviewTreeEditable is now both an ReviewEditable and ReviewNodeExpandable. Now simply a wrapper for a ReviewNodeExpandable with a ReviewEditable as root so that neither is exposed.

Similarly for ReviewTree vis-a-vis ReviewTree and ReviewNode.
Some javadoc stuff and simplification of Review class hierarchy.

ReviewTreeEditable is now both an ReviewEditable and ReviewNodeExpandable. Now simply a wrapper for a ReviewNodeExpandable with a ReviewEditable as root so that neither is exposed.

Similarly for ReviewTree. Now implements ReviewNode instead of Review.