Merge branch 'jk/diff-highlight-more'

Various updates to contrib/diff-highlight, including documentation updates, test improvements, and color configuration handling. * jk/diff-highlight-more: diff-highlight: fetch all config with one process diff-highlight: allow module callers to pass in color config diff-highlight: test color config diff-highlight: use test_decode_color in tests t: add matching negative attributes to test_decode_color diff-highlight: check diff-highlight exit status in tests diff-highlight: drop perl version dependency back to 5.8 diff-highlight: mention build instructions