Allow inline formatting in headers
Ignore leading whitespace in headers
Allow ATX headers to be indented
Allow closing # for ATX headers
Detect characters after closing # in ATX headers
Let atx headers interrupt paragraphs
Support empty atx headers
Allow h1 and h2 setext headers
Allow setext headers to be indentend
Allow empty lines in code blocks
Refactor setext headers
Support trailing backslashes
Implement simple HTML escaping