* ph/diffopts:
  Reorder diff_opt_parse options more logically per topics.
  Make the diff_options bitfields be an unsigned with explicit masks.
  Use OPT_BIT in builtin-pack-refs
  Use OPT_BIT in builtin-for-each-ref
  Use OPT_SET_INT and OPT_BIT in builtin-branch
  parse-options new features.