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.

gstlal-inspiral/bin/gstlal_inspiral_mass_model

@@ -106,8 +106,8 @@ for row in sngl_inspiral_table:
 		prob[row.template_id] /= TEMPDENS(mchirp)
 
 	elif options.model == "uniform-template":
-                hdist = sorted([HorizonDistance(15, 1024, 1./4., row.mass1, row.mass2, (0., 0., row.spin1z), (0., 0., row.spin2z))(psd[ifo])[0] for ifo in psd.keys()])
-                prob[row.template_id] = 1.0 / (hdist[-options.min_instrument]**3)
+		hdist = sorted([HorizonDistance(15, 1024, 1./4., row.mass1, row.mass2, (0., 0., row.spin1z), (0., 0., row.spin2z))(psd[ifo])[0] for ifo in psd.keys()])
+		prob[row.template_id] = 1.0 / (hdist[-options.min_instrument]**3)
 
 	elif options.model == "bbh":
 		#