Reader for tab-delimited text that's (slightly) friendlier than the
stock Python csv module (which isn't intended for direct use by
humans anyway, and neither was this package originally, but that
seems to be the way that it has evolved...).
Columns parameter specifies how many columns users of the reader
expect to see; lines with fewer columns will be padded with None
values.
Original API design for this class courtesy of Warren Kumari, but
don't blame him if you don't like what I did with his ideas.
Definition at line 475 of file myrpki.py.