ENH,UBY: newtab.js: optional {open in new tab, show a:visited} checkboxes & cookies

[westurner]

• https://github.com/js-cookie/js-cookie (MIT License)
  • https://github.com/js-cookie/js-cookie/commit/81aeea1
• closes westurner/wiki#7
• closes westurner/wiki#15