Merge branch 'jc/maint-grep-untracked-exclude' into jc/grep-untracked-exclude

* jc/maint-grep-untracked-exclude: grep: teach --untracked and --exclude-standard options grep --no-index: don't use git standard exclusions grep: do not use --index in the short usage output Conflicts: Documentation/git-grep.txt builtin/grep.c