Corrected typo and extended allowed types for MultiSegmentRecord

[agent3gatech]

Corrected misordered arguments in util.lines_to_file. Added 'list' as allowed types for seg_name and seg_len, for when writing MultiSegmentRecords.

[bemoody]

Thanks!

In case it's not clear, here's an example which doesn't work prior to this change:

>>> import wfdb
>>> r = wfdb.rdheader('3000003', pn_dir='mimic3wdb/1.0/30/3000003')
>>> r.wrheader()

Probably nobody tested this code path, and the logic is hard to follow. This change should fix the immediate problem.

But I think what we really want is, rather than changing the types in SEGMENT_SPECS, we want to add "seg_name" and "seg_len" to LIST_FIELDS (wfdb/io/record.py, line 1675.)