Rewrite

[thblt]

This first version is a butched draft. A complete version should support:

• at the very least, noweb
• if possible, default values for header arguments in document preamble.

Quick notes for a possible rewriting:

• Use Haskell! Pandoc can do 99% of the job. A Pandoc AST holds the code blocks with header arguments parsed, and extra indentation removed. Only noweb would remain to handle.
• noweb can also be used to include the results of a code block, by including it like this:

   <<block_name(optional arguments)>>
  

  I don't think I'll ever support this, as it would mean rewriting most of org-babel, and I really don't see a use case for it. (Also, code blocks could be elisp, which means actually running from inside Emacs)
• A different approach to noweb could be to let Org handle it, if it's not too slow. Let org expand noweb references, capture the result and tangle.
• Parsing org headers is probably hard, replacing them with command-line arguments would be easier.