More "ORT" merge strategy.
* en/merge-ort-2:
merge-ort: add modify/delete handling and delayed output processing
merge-ort: add die-not-implemented stub handle_content_merge() function
merge-ort: add function grouping comments
merge-ort: add a paths_to_free field to merge_options_internal
merge-ort: add a path_conflict field to merge_options_internal
merge-ort: add a clear_internal_opts helper
merge-ort: add a few includes