v6.0.0

• Fix Bug: .visuallyhidden on macOS VO fixes #1985 (#1989)
• Adds web app manifest file (#1963)
• Update to jQuery 3.2.1 (#1942)
• Improve ::selection documentation which became confusing after c7057be (#1955)
• refactor(html): update browsehappy to https instead of http (#1952)
• Fix links to CONTRIBUTING.md (#1951)
• Adds .github folder and contents Fixes (#1948)
• Modernizr 3, modernizr.config and (#1940)
• Housekeeping by @coliff (#1968 #1969 #1965 #1964 #1958 #1957 #1956)
• Update .gitattributes for Web Projects (#1935)
• Add the link for useful .gitignore templates (#1936)
• Node plumbing updated (#1925) (#1928) (#1931)
• Use es2015 syntax in mocha tests (#1788)
• Scope :first-letter selector for print styles (#1904)
• Add SRI Hash for jQuery (#1904)
• Update .jshintrc (#1903)
• Improve accessibility with visuallyhidden content (#1900)
• Tell users that IE 8 and 9 are outdated
  (#1747).
• Removed IE8 Support (upgrades jQuery and normalize.css to latest)
  (#1524).
• Fix print styles for Internet Explorer 11
  (#1799).
• Update doc links to https
  (#1889).
• Delete crossdomain.xml
  (#1881).
• Adds pre-wrap to PRE
  (#1742).
• Change license format to SPDX format
  (#1814).
• Simplify the Google Analytics snippet using async & defer (#1660).