title: Update minimum spanning tree with modification of edge
body: <p>A graph (positive weight edges) with a MST
  If some edge, e is modified to a new value, what is the best way to update the MST without completely remaking it. I think this can be done in linear time. Also, it seems that I would need a different algorithm based on whether 1) e is already a part of the MST and 2) whether the new edge, e is larger or smaller than the original</p>