Merge branch 'jc/add-resolved' into jch

'git add' has been taught a new '--resolved' option to stage conflict-resolved paths, while leaving unrelated local changes unstaged. It scans the unmerged paths for leftover conflict markers and aborts if any are found. * jc/add-resolved: add: introduce '--resolved' option read-cache: add remove_file_from_index_with_flags() merge-ll: consolidate conflict marker scanning logic read-cache: reindent