Loads the topology file (e.g. GRO,PDB,INPCRD) as a MDAnalysis Universe,
        checks if it can be loaded. Needs to be run before the equivalent function
        topol.load_trajectory() and provides the snapshot that is going to be used
        for final residue placement - i.e. the residue coordinates for placement
        are taken from this file.
            Takes:
              * topology * - a topology file e.g. GRO, PDB, INPCRD, CARD, DMS
            Output:
              * self.universe * - MDAnalysis Universe

def load_topology(self,topology):
        """
        Loads the topology file (e.g. GRO,PDB,INPCRD) as a MDAnalysis Universe,
        checks if it can be loaded. Needs to be run before the equivalent function
        topol.load_trajectory() and provides the snapshot that is going to be used
        for final residue placement - i.e. the residue coordinates for placement
        are taken from this file.
            Takes:
              * topology * - a topology file e.g. GRO, PDB, INPCRD, CARD, DMS
            Output:
              * self.universe * - MDAnalysis Universe
        """

        try:
            self.universe = MDAnalysis.Universe(topology)
        except ValueError:
            print "Check your topology file - it is either missing or misspelled."
            sys.exit()