Merge branch 'maint'

Merge branch 'maint'

* maint:
  Start preparing for 1.5.3.6
  git-send-email: Change the prompt for the subject of the initial message.
  SubmittingPatches: improve the 'Patch:' section of the checklist
  instaweb: Minor cleanups and fixes for potential problems
  stop t1400 hiding errors in tests
  Makefile: add missing dependency on wt-status.h
  refresh_index_quietly(): express "optional" nature of index writing better
  Fix sed string regex escaping in module_name.
  Avoid a few unportable, needlessly nested "...`...".
  git-mailsplit: with maildirs not only process cur/, but also new/

Signed-off-by: Junio C Hamano <gitster@pobox.com>