Third batch to teach the diff machinery to use the parse-options
API.
* nd/diff-parseopt-3:
diff-parseopt: convert --submodule
diff-parseopt: convert --ignore-submodules
diff-parseopt: convert --textconv
diff-parseopt: convert --ext-diff
diff-parseopt: convert --quiet
diff-parseopt: convert --exit-code
diff-parseopt: convert --color-words
diff-parseopt: convert --word-diff-regex
diff-parseopt: convert --word-diff
diff-parseopt: convert --[no-]color
diff-parseopt: convert --[no-]follow
diff-parseopt: convert -R
diff-parseopt: convert -a|--text
diff-parseopt: convert --full-index
diff-parseopt: convert --binary
diff-parseopt: convert --anchored
diff-parseopt: convert --diff-algorithm
diff-parseopt: convert --histogram
diff-parseopt: convert --patience
diff-parseopt: convert --[no-]indent-heuristic