Implementation of Algorithm 2.1 - Kruskal's minimum cost spanning tree.
Author:  Ryan McIntyre

Input is a text file representing the adjacency / cost matrix of a 
weighted, undirected graph. Input should contain n lines. Each line
is a comma-separated list of costs. If (i,j) is an edge with cost c>0, 
then position (i,j) will contain "c". If (i,j) is not an edge, 
then position (i,j) is simply 0. A sample input has been provided.

Output is list of edges which form a minimum cost spanning tree of 
the graph.
