vimwiki panvimwiki markdownlint gfm

• Journal 2024-02-17 selected gfm for citeproc output because markdownlint recognizes the anchors, whereas the default pandoc anchors would require disabling MD051/link-fragments.
• Defines tests for task_lists behavior.
• If a task_lists contains blank lines, pandoc will split every item in adjacent unordered lists with a blank line. Break with a comment or other text to split the list.
• Pandoc coerces asterisk unordered list-markers to hyphens and escapes octothorpes (#), which breaks Taskwiki syntax.
• Github and Myst have different implicit heading links:
  • Myst: #g-panvimwiki-settings
  • Github: #gpanvimwiki_settings

      See [g:panvimwiki_settings].
    
      ## g:panvimwiki_settings
    
      To link here.
    
      <!-- markdownlint-disable MD051 -->
      [g:panvimwiki_settings]: #g-panvimwiki-settings