Update methods that deal with downloaded files

Update methods that deal with downloaded files

• Update methods that deal with downloaded files
  -- (Chromium Guest Mode forces the default downloads folder)
• Improve compatibility for older versions of Python
  -- (Some methods had issues for older Python versions)
• Update Python dependencies:
  -- prompt-toolkit==3.0.16;python_version>="3.6"
  -- cffi==1.14.5