Merge branch 'jn/help-everywhere'

Merge branch 'jn/help-everywhere'

* jn/help-everywhere: (23 commits)
  diff --no-index: make the usage string less scary
  merge-{recursive,subtree}: use usagef() to print usage
  Introduce usagef() that takes a printf-style format
  Let 'git <command> -h' show usage without a git dir
  Show usage string for 'git http-push -h'
  Let 'git http-fetch -h' show usage outside any git repository
  Show usage string for 'git stripspace -h'
  Show usage string for 'git unpack-file -h'
  Show usage string for 'git show-index -h'
  Show usage string for 'git rev-parse -h'
  Show usage string for 'git merge-one-file -h'
  Show usage string for 'git mailsplit -h'
  Show usage string for 'git imap-send -h'
  Show usage string for 'git get-tar-commit-id -h'
  Show usage string for 'git fast-import -h'
  Show usage string for 'git check-ref-format -h'
  http-fetch: add missing initialization of argv0_path
  Show usage string for 'git show-ref -h'
  Show usage string for 'git merge-ours -h'
  Show usage string for 'git commit-tree -h'
  ...

Conflicts:
	imap-send.c