Python code for Morgan-Higgs indirect method

This code calls "RNAsubopt -p" from Vienna RNA Package. Before running the main program, dijkstraMorganHiggsViaSamplingUsingRNAsubopt.py, be sure to have executable "RNAsubopt" from Vienna Package in working directory. Our implementation of Morgan-Higgs indirect method uses a simple variant of Dijkstra's single source, shortest path algorithm, to create an indirect path by stitching together multiple "hops" between low energy structures sampled by RNAsubopt.