ENH: make read_raw_segment into a method called read_segment
REN: read_raw_segment to read_segment
ENH: make read_raw_segment into a method called read_segment

ENH: pep8

ENH: spell
ENH: make read_segment, read_segment_times PRIV
ENH: make read_segment PRIV
FIX: indexing for append method
Merge pull request #499 from t3on/tb-raw

ENH: make read_raw_segment into a method called read_segment