Breaking changes

• Remove substitutions #1532
• Separate source into modules #1563 #1572 #1573 #1575 #1576 #1581

Fixes

• Fix relative urls in baseUrl option #1526
• Loose task list #1535
• Fix image parentheses #1557
• remove module field & update devDependencies #1581

Docs

• Update examples with es6+ #1521
• Fix link to USING_PRO.md page #1552
• Fix typo in USING_ADVANCED.md #1558
• Node worker threads are stable #1555

Dev Dependencies

• Update deps #1516
• Update eslint #1542
• Update htmldiffer async matcher #1543