Ok,

So this is really more of a complete rewrite than a bunch of patches, but it's just a picture of what IMHO is a saner way to do this module.  I suppose I could refactor alot of it to look more like the old module, but I'm still not sure what would be better, in terms of having seperate visitors to walkers.  Either way, the terminology in the original wasn't much clearer.

At bare minimum though, i got postorder implemented, so this code has got to be worth something valuable... I hope....

Feedback please.