Security Fixes

• Fix unsafe heading regex (#1224)
• Fix unsafe link regex (#1223, #1227)

New Features

• Add option to disable heading ids (#1190)
• Add support for GFM Task Lists to comply with the GFM spec (#1250)

Breaking Changes

• Fix escaping pipes in tables (#1239)
• Fix html output for tables to match GFM spec (#1245)
• Fix many bugs to reach parity with CommonMark spec (#1135)
• Fix new Renderer() so it uses default options (#1203)
• Fix text and paragraph return types (#1248) (#1249)
• Fix <em> less than 3 chars (#1181)
• Fix <pre> code blocks so there is no more trailing \n (#1266)
• Fix default langPrefix to follow CommonMark standard language- (#1265)

CLI Changes

• Add string argument to CLI (#1182)
• Change CLI stdio to remove warning (#994)

Other changes

• Lint all the things (#1185)
• Improved testing and DevOps (#1160, #1210, #1220, #1228, #1219, #1256)
• Update documentation and demos (#1196, #1197, #1204, #1207, #1221, #1233, #1217, #1240, #1244, #1253)