Merge branch 'jk/options-cleanup'

Various clean-ups to the command line option parsing. * jk/options-cleanup: apply, ls-files: simplify "-z" parsing checkout-index: disallow "--no-stage" option checkout-index: handle "--no-index" option checkout-index: handle "--no-prefix" option checkout-index: simplify "-z" option parsing give "nbuf" strbuf a more meaningful name