2.1.0

• Bumped mdn-data to 2.0.27
• Added module field to package.json
• Fixed minor issues in CommonJS version
• Fixed css-tree/utils export (#181)
• Added css-tree/convertor export
• Added css-tree/selector-parser export (~27kb when bundled, #183)
• Reduced bundle size:
  • css-tree/parser 50kb -> 41kb
  • css-tree/generator 46kb -> 23kb
• Renamed syntaxes into types in css-tree/definition-syntax-data-patch
• Added parsing support for :is(), :-moz-any(), :-webkit-any() and :where() (#182, #184)