returning a visited-edge seems to be a better interface than returning
just the visited-vertex.
Merge branch 'master' of https://github.com/anupamk/common-utilz

* 'master' of https://github.com/anupamk/common-utilz:
  returning a visited-edge seems to be a better interface than returning just the visited-vertex.

Conflicts:
	graph/traversal/graph_traversal.go