ls-files -o: optionally skip showing the contents in "untracked" directories

ls-files -o: optionally skip showing the contents in "untracked" directories

Darrin Thompson notes that git-ls-files -o reports all the unknown
files it finds in a work area.  Subversion and probably other systems
"simply ignore all the files and directories inside an unknown
directory and just note the directory as unknown."

With --directory option, ls-files --others shows untracked directories
without descending into them.

Signed-off-by: Junio C Hamano <junkio@cox.net>