[ Chris Lamb ]
* Update tests for file 5.39. (Closes: reproducible-builds/diffoscope#179)
* Downgrade the tlsh warning message to an "info" level warning.
  (Closes: #888237, reproducible-builds/diffoscope#29)
* Use the CSS "word-break" property over manually adding U+200B zero-width
  spaces that make copy-pasting cumbersome.
  (Closes: reproducible-builds/diffoscope!53)

* Codebase improvements:
  - Drop some unused imports from the previous commit.
  - Prevent an unnecessary .format() when rendering difference comments.
  - Use a semantic "AbstractMissingType" type instead of remembering to check
    for both "missing" files and missing containers.

[ Jean-Romain Garnier ]
* Allow user to mask/filter reader output via --diff-mask=REGEX.
  (MR: reproducible-builds/diffoscope!51)
* Make --html-dir child pages open in new window to accommodate new web
  browser content security policies.
* Fix the --new-file option when comparing directories by merging
  DirectoryContainer.compare and Container.compare.
  (Closes: reproducible-builds/diffoscope#180)
* Fix zsh completion for --max-page-diff-block-lines.

[ Mattia Rizzolo ]
* Do not warn about missing tlsh during tests.