Assorted fixes

While doing some cleanup with the unused imports, I also ran into various issues throughout that this MR fixes:

• Port various python2 print statements throughout
• gstlal_inspiral_calc_snr: Move missing_required_options upstream to avoid running into issues where it hasn't been defined yet
• Fix a couple of StringIO() calls that were not correct. (if StringIO is imported from io, it should be StringIO(), not StringIO.StringIO().
• chirptime.py file had Windows formatting, so that was converted via dos2unix
• Fix a couple of undefined variable problems due to typos.
• Remove unused variable in segments.py
• Fix wrong return type annotation in segments.py.