Long-overdue rename.
No longer needed - functionality rolled into XmlToAvroPathCreator.
(Which will also get a rename, eventually.)
Moving & shaking: XmlSchemaDocumentPathNode wraps either an
XmlSchemaDocumentNode (if it exists) or an XmlSchemaStateMachineNode (if
the corresponding XmlSchemaDocumentNode needs to be created).
Making the document node set-able (will be needed later when registering
a path with the corresponding document node.

Adding a toString for the state machine node, should make things easier
to debug.
Updating print-out of state machine.

Turns out the state names can be huge when dealing with complex records.
Path management.  Create new nodes, clone them, add children, recycle.
Follows the document along the way and appropriately links it all
together.

Unclear how to handle the root node of a path being its own entity, and
not a clone.
Flushed out the path manager, including following & unfollowing paths.

Not sure if I committed my work to build a tree of possiblities, but it
turned out to not be feasible.  I only have access to the element names
when trying to follow new possiblities, so all possible paths must be
rooted at an element.  Likewise, I cannot create branches at arbitrary
locations in the path.
Switch to using the path manager.