[PATCH 0/4] doc-diff: support diffing from/to AsciiDoc(tor)

I've taught `doc-diff` a few new knobs to support usage like

  $ ./doc-diff --from-asciidoc --to-asciidoctor HEAD HEAD

and I don't think I've messed it up too badly in the process. I'm open to the idea that this might not be interesting to a whole lot of people. But I have made some progress on fixing up Asciidoctor *and* AsciiDoc issues using this, and once the output of the above command is empty -- which might not be too far off -- it could be interesting to try and keep it that way using a bit of automation around these switches.

While using/testing these patches, I've made some progress on the rendering of the headers and footers in Asciidoctor [1], so the `--cut-header-footer` switch that I'm adding in the final patch might hopefully not be necessary for too long. But we'd still need a `--cut-footer` switch -- at least I would, on my system [2]. If this series is considered generally sane, I'd be happy to rework the final patch to `--cut-header` if that's preferred.

Patch 1 has a minor purely-textual merge conflict with ma/asciidoctor-fixes.

[1] https://public-inbox.org/git/20190317144747.2418514-1-martin.agren@gmail.com/

[2] After [1], the date in the footer is still formatted differently
    here. It might be a locale thing, and I tend to shy away from even
    trying to understand those. :-/

Martin Ågren (4):
  Doc: auto-detect changed build flags
  doc-diff: let `render_tree()` take an explicit directory name
  doc-diff: support diffing from/to AsciiDoc(tor)
  doc-diff: add `--cut-header-footer`

 Documentation/.gitignore |  1 +
 Documentation/Makefile   | 23 ++++++++---
 Documentation/doc-diff   | 86 +++++++++++++++++++++++++++++++++-------
 3 files changed, 90 insertions(+), 20 deletions(-)