-  avoid org-mode undefined behavior, provide
   unique code-block names

- new dir for markup tools
  misc/util/d/tools/markup_conversion
- start looking at tools for converting
  - endnotes from binary to inline
  - sisu.rb to sisu spine in d
  - look at conversion of document headers to yaml
    from
    - bespoke sisu headers (original .rb)
    - sdlang
    - toml

- the good
  - works
  - project looks pretty clean
- the bad
  - subprojects built externally
  - not suitable for debian packaging

- subprojects with "manual" git download where
  upstream git lacks meson.build
- imageformats git tag (version) pinned, else
  build fails