tonyrog/yang — pull request #1 by RoadRunnr (2012-11-26 18:01:38+00:00)
Title: implement uses:augment and enhance refine

augment and refine as substaments of "uses"take a relative node
identifier. A simple keylookup is therefore not sufficient and
replaced by recursive traversing the uses substructure.

augment and refine are similar enough that they can be folded into
the same logic. THe only difference beening that augment add new
nodes while refine edits existing ones.

finaly, augment might add new nodes that contain uses, so those
need to be expanded as well.