TreeWalker, NodeIterator

Questions:
1.  TreeWalker.getParentNode() returns an ancestor, not necessarily the
parent.  Should it not be renamed getAncestorNode() to reflect the
semantics?
2.  TreeWalker.getFirstChild()/getLastChild() apparently don't drill down,
but only return "direct" offspring.  Can you confirm this/clarify the
specification.

Comments:
The implementation of TreeWalker [especially in light of the "live" nature
of TreeWalkers] would benefit from a detach() method, like that found in
NodeIterator.  That said, adding detach() to TreeWalker gives this interface
a signature that would allow it to be an extension of NodeIterator.

	Keith