Merge branch 'maint'

* maint:
  git-send-email.txt: move --format-patch paragraph to a proper location
  git-shortlog.txt: improve documentation about .mailmap files
  pretty: support multiline subjects with format:
  pretty: factor out format_subject()
  pretty: factor out skip_empty_lines()
  merge-file: handle freopen() failure
  daemon: cleanup: factor out xstrdup_tolower()
  daemon: cleanup: replace loop with if
  daemon: handle freopen() failure
  describe: Avoid unnecessary warning when using --all