Read annotation file and store a list of namedtuples.

def _init_associations(self, fin_gaf, hdr_only, prt, allow_missing_symbol):
        """Read annotation file and store a list of namedtuples."""
        ini = InitAssc()
        nts = ini.init_associations(fin_gaf, hdr_only, prt, allow_missing_symbol)
        self.hdr = ini.hdr
        return nts