Merge branch 'cc/replace-edit'

"git replace" learns a new "--edit" option. * cc/replace-edit: Documentation: replace: describe new --edit option replace: add --edit to usage string replace: add tests for --edit replace: die early if replace ref already exists replace: refactor checking ref validity replace: make sure --edit results in a different object replace: add --edit option replace: factor object resolution out of replace_object replace: use OPT_CMDMODE to handle modes replace: refactor command-mode determination