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

@@ -740,7 +740,7 @@ for output_file_number, (svd_bank_url_dict, output_url, ranking_stat_output_url,
 		xmldoc = ligolw.Document()
 		xmldoc.appendChild(ligolw.LIGO_LW())
 		map(xmldoc.childNodes[-1].appendChild(sngl_inspiral_table.copy()).append, sngl_inspiral_table)
-		output = StringIO.StringIO()
+		output = StringIO()
 		ligolw_utils.write_fileobj(xmldoc, output, compress = "gz")
 		outstr = output.getvalue()
 		output.close()