- Get all B::Deparse tests working
- Get more of Perl distribution tests round-tripping:
  deparse test, run deparsed test which should succeed
- Refactor more common parts of 5.20 and 5.22 out
- Better tree structure. Bodies could have subparts tagged
- texts could have more structure: nested lists with different
  separators per list.
- Cleaner output based on more sophisticated tree analysis
- Distinguish a node skipped from above or from below.
- make indentation less hacky using tagging outside of text.
  (Perl::Tidy is what folks should use for fancier indentation)