pretty: add %D format specifier

Add a new format specifier, '%D' that is identical in behaviour to '%d',
except that it does not include the ' (' prefix or ')' suffix provided
by '%d'.

Signed-off-by: Harry Jeffery <harry@exec64.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'hj/pretty-naked-decoration' into jch

* hj/pretty-naked-decoration:
  pretty: add %D format specifier

# Conflicts:
# 	log-tree.c
Merge branch 'sp/stream-clean-filter' into jch

Rerolled.  Comments & reviews?

* sp/stream-clean-filter:
  convert: stream from fd to required clean filter to reduce used address space
  copy_fd(): do not close the input file descriptor
  mmap_limit: introduce GIT_MMAP_LIMIT to allow testing expected mmap size
  memory_limit: use git_env_ulong() to parse GIT_ALLOC_LIMIT
  config.c: add git_env_ulong() to parse environment variable
  convert: drop arguments other than 'path' from would_convert_to_git()

# Conflicts:
# 	wrapper.c
Merge branch 'tr/remerge-diff' into jch

"log -p" output learns a new way to let users inspect a merge
commit by showing the differences between the automerged result
with conflicts the person who recorded the merge would have seen
and the final conflict resolution that was recorded in the merge.

Review comments sent.

* tr/remerge-diff:
  log --remerge-diff: show what the conflict resolution changed
  name-hash: allow dir hashing even when !ignore_case
  merge-recursive: allow storing conflict hunks in index
  merge_diff_mode: fold all merge diff variants into an enum
  combine-diff: do not pass revs->dense_combined_merges redundantly
  merge-recursive: -Xindex-only to leave worktree unchanged
  merge-recursive: internal flag to avoid touching the worktree
  merge-recursive: remove dead conditional in update_stages()

# Conflicts:
# 	merge-recursive.c
Merge branch 'da/rev-parse-verify-quiet' into jch

* da/rev-parse-verify-quiet:
  stash: prefer --quiet over shell redirection of the standard error stream
  refs: make rev-parse --quiet actually quiet
  t1503: use test_must_be_empty
  Documentation: a note about stdout for git rev-parse --verify --quiet
Merge branch 'da/include-compat-util-first-in-c' into jch

* da/include-compat-util-first-in-c:
  SQUASH???
  check-headers: add header usage checks for .c files
  Makefile: add check-headers target
  cleanups: ensure that git-compat-util.h is included first