Merge branch 'jc/show-usage-help'

The help text from "git $cmd -h" appear on the standard output for some $cmd and the standard error for others. The built-in commands have been fixed to show them on the standard output consistently. * jc/show-usage-help: builtin: send usage() help text to standard output oddballs: send usage() help text to standard output builtins: send usage_with_options() help text to standard output usage: add show_usage_if_asked() parse-options: add show_usage_with_options_if_asked() t0012: optionally check that "-h" output goes to stdout