commonmark 0.29.2

• Use ES modules (Iddan Aaronsohn).
• Improve and simplify reference link normalization (#168).
  We now use the built in str.toLowerCase().toUpperCase(), which
  @rlidwka has shown does an accurate unicode case fold.
  This allows us to remove a huge lookup table and should
  both decrease the size of the library and speed things up.
• Fix end source position for nested or indented fenrced code blocks.
  Improves on earlier fix to #141, which only worked for code blocks
  flush with the left margin.
• Upgrade to entities 2.0+.
• Fix generation of dist files for dingus.
• Use esm for bin/commonmark, bench, test.
• Use rollup uglify plugin to create minified dist.
• Move dev dependencies to proper place in package.json.
• Use rollup instead of browserify (Iddan Aaronsohn).
• Reformat code with prettier (Iddan Aaronsohn).
• Replace travis CI with GitHub Actions CI.
• Bump versions of software to benchmark against.
• Change jgm/commonmark.js to commonmark/commonmark.js (#126).
• Security audit fixes.
• Remove obsolete spec2js.js script
• Remove test on node 9 and under. Only support actively maintained
  versions.
• Run npm lint in ci.