zsh completion: add new options for existing commands * backout: add --tool; * bisect: add --extend; * bookmarks: add --inactive; * branches: add --closed; * bundle: add --rev, --all, --branch; * cat: add --decode; * clone: add --updaterev, --branch, --pull and use common-with-qclone opts; * commit: add --close-branch; * diff: add --change, --reverse, --stat, --text, --unified; * export: add --rev; * grep: add --date; * heads: add --topo, --closed; * help: add --extension, --command, --keywords; complete additional help topics also, not commands only; * identify: add --bookmark and remote_opts; * import: add --no-commit, --exact, --import-branch, --date, --user, --similarity and commit options; * log: add --user, --date, --stat, --git, --graph; * manifest: add --rev; * push: add --new-branch; * resolve: add --all, --no-status, --tool and pattern options; * revert: add --date; * serve: add --prefix, --web-conf, --pid-file, --cmdserver, --certificate; * status: add --change; * tag: add --force, --edit, --remove; * tip: add --git; * update: add --check, --date.