Document the `native_figures` extension.

Update changelog, AUTHORS.

Use correct architecture in .tar.gz for linux.

Update README and man page.

CircleCI: fix stack installation.

homebrew no longer has a bottle for haskell-stack for the
old macOS version we're building on.

Bump to 2.11.3.1 and update changelog and man page.

Update RELEASE-CHECKLIST for CircleCI.

Update README.md, man page.

Bump to 2.11.1.1 and update changelog.

Update man page and changelog.