v2, 3 partsServer side automatic tag following

This series replaces my prior one from this evening based on Nico's suggestion to use "--auto-include-tag" as the option name. Its effectively the same series, but every commit is different due to the change in option name and protocol extension.

For those new to the series, it avoids the second connection needed to download new annotated tags. Instead the server side automatically sends the tag if the client signals it would do automated tag following. This lightens the load on the server and on the client as its one less connection required to per client requesting updates.

  1)  git-pack-objects: Automatically pack annotated tags if object was packed
  2)  Teach fetch-pack/upload-pack about --auto-include-tag
  3)  Teach git-fetch to exploit server side automatic tag following

 Documentation/git-fetch-pack.txt   |    8 +++-
 Documentation/git-pack-objects.txt |    5 ++
 builtin-fetch-pack.c               |    9 +++-
 builtin-fetch.c                    |    3 +
 builtin-pack-objects.c             |   24 +++++++++-
 fetch-pack.h                       |    3 +-
 t/t5305-auto-include-tag.sh        |   84 ++++++++++++++++++++++++++++++++++++
 t/t5503-tagfollow.sh               |   26 +++++++++++
 transport.c                        |    5 ++
 transport.h                        |    3 +
 upload-pack.c                      |   10 +++-
 11 files changed, 172 insertions(+), 8 deletions(-)