• Dropped support for end-of-life Python versions 2.6, 3.2, 3.3. (#199, #204)
• Fixed signals getting stuck inside the C tokenizer until parsing finishes,
  in pathological cases. (#206)
• Fixed not being considered a single-only tag. (#200)
• Fixed a C tokenizer crash on Python 3.7 when compiled with assertions. (#208)
• Cleaned up some minor documentation issues. (#207)