Prototype the markdown parser

[namse]

• Leaf
  • Thematic breaks
  • ATX headings
  • Setext headings
  • Indented code blocks
  • Fenced code blocks
  • HTML blocks
  • Link reference definitions
  • Paragraphs
  • Blank lines
• Container blocks
  • Block quotes
  • List items
  • Lists
• Inlines
  • Backslash escapes
  • Entity and numeric character references
  • Code spans
  • Emphasis and strong emphasis
  • Links
  • Images
  • Autolinks
  • Raw HTML
  • Hard line breaks
  • Soft line breaks
  • Textual content