Make more commands builtin

 Makefile                               |   26 +++++++++++++++-----------
 apply.c => builtin-apply.c             |    3 ++-
 commit-tree.c => builtin-commit-tree.c |    3 ++-
 diff-files.c => builtin-diff-files.c   |    3 ++-
 diff-index.c => builtin-diff-index.c   |    3 ++-
 diff-stages.c => builtin-diff-stages.c |    3 ++-
 diff-tree.c => builtin-diff-tree.c     |    3 ++-
 ls-files.c => builtin-ls-files.c       |    3 ++-
 ls-tree.c => builtin-ls-tree.c         |    3 ++-
 read-tree.c => builtin-read-tree.c     |    3 ++-
 show-branch.c => builtin-show-branch.c |    3 ++-
 tar-tree.c => builtin-tar-tree.c       |    3 ++-
 builtin.h                              |   12 ++++++++++++
 git.c                                  |   13 ++++++++++++-

I've tried to follow the trend of making commands builtin.
All patches have the same form.  This is my first use
of git-send-email, so this might come out wrong.

Peter Eriksen [off-list ref]