Merge branch 'jn/gitweb-side-by-side-diff'

* jn/gitweb-side-by-side-diff: gitweb: Add navigation to select side-by-side diff gitweb: Use href(-replay=>1,...) for formats links in "commitdiff" t9500: Add basic sanity tests for side-by-side diff in gitweb t9500: Add test for handling incomplete lines in diff by gitweb gitweb: Give side-by-side diff extra CSS styling gitweb: Add a feature to show side-by-side diff gitweb: Extract formatting of diff chunk header gitweb: Refactor diff body line classification