Make 5 bones.
Add debug.
Add debug.
Add debug.
Add debug.
Add debug.
Add on_changed().
Add on_changed().
Include the header for getenv().
Allow bones to be animated too.
Add a member to store the parent valuenode.  Needed to make the reference counting work.
Keep parent_node_ up to date.
When displaying the list of bones, sort by the bones' names at time 0.
Don't show bones with no references.
Define ref() and unref() as virtual so they can be overridden in derived classes.
Declare ref() and unref().
I'm trying to understand why the destructor isn't being called.  Overriding ref() and unref().
Add debugging.  Show ref counts as well as rref counts.
'ahead' is one word.
Let's just remember the most recent action's name, rather than the action itself.