Read GAF file. Store annotation data in a list of namedtuples.

def init_associations(self, fin_gaf, hdr_only, prt, allow_missing_symbol):
        """Read GAF file. Store annotation data in a list of namedtuples."""
        import timeit
        tic = timeit.default_timer()
        nts = self._read_gaf_nts(fin_gaf, hdr_only, allow_missing_symbol)
        # GAF file has been read
        if prt:
            prt.write('HMS:{HMS} {N:7,} annotations READ: {ANNO}\n'.format(
                N=len(nts), ANNO=fin_gaf,
                HMS=str(datetime.timedelta(seconds=(timeit.default_timer()-tic)))))
        # If there are illegal GAF lines ...
        if self.datobj:
            if self.datobj.ignored or self.datobj.illegal_lines:
                self.datobj.prt_error_summary(fin_gaf)
        return nts