[PATCH v2 00/14] Sparse checkout

Main changes from the last round are:
 - The name is now "sparse checkout"
 - "git clone --path" => "git clone --narrow-path"
 - "git checkout --path" => "git checkout --reset-path"
 - New narrow spec (or "sparse patterns" from now) resembles
   .gitignore patterns
 - "git ls-files" now supports more fine-grained listing. It can now
   list checkout files, no-checkout files or orphaned (previously
   "overlay") files. --overlay is gone
 - "git status" shows orphaned entries and remedies
 - Documentation has been restructured to accompany code changes.
   Thanks to Jakub, Baz for lots of input.

For code changes, significant changes are:
  [03/14] ls-files: add options to support sparse checkout
  [10/14] ls-files: support "sparse patterns", used to form sparse checkout areas

I hope I have addressed all the issues. If I miss anything, please speak up.

Nguyễn Thái Ngọc Duy (14):
  Extend index to save more flags
  Introduce CE_NO_CHECKOUT bit
  ls-files: add options to support sparse checkout
  update-index: refactor mark_valid() in preparation for new options
  update-index: add --checkout/--no-checkout to update CE_NO_CHECKOUT bit
  ls-files: Add tests for --sparse and friends
  Prevent diff machinery from examining worktree outside sparse checkout
  checkout_entry(): CE_NO_CHECKOUT on checked out entries.
  grep: skip files outside sparse checkout area
  ls-files: support "sparse patterns", used to form sparse checkout areas
  unpack_trees(): add support for sparse checkout
  clone: support sparse checkout with --narrow-path option
  checkout: add new options to support sparse checkout
  wt-status: Show orphaned entries in "git status" output

 .gitignore                            |    1 +
 Documentation/git-checkout.txt        |  131 ++++++++++++++++++++-
 Documentation/git-clone.txt           |   10 ++-
 Documentation/git-grep.txt            |    4 +-
 Documentation/git-ls-files.txt        |   30 +++++-
 Documentation/git-update-index.txt    |   13 ++
 Makefile                              |    2 +-
 builtin-checkout.c                    |   37 ++++++
 builtin-clone.c                       |   13 ++
 builtin-grep.c                        |    7 +-
 builtin-ls-files.c                    |   60 +++++++++-
 builtin-update-index.c                |   40 ++++---
 cache.h                               |   69 ++++++++++-
 diff-lib.c                            |    5 +-
 diff.c                                |    4 +-
 entry.c                               |    1 +
 read-cache.c                          |   57 +++++++--
 t/t2011-checkout-sparse.sh            |  108 +++++++++++++++++
 t/t2104-update-index-no-checkout.sh   |   36 ++++++
 t/t3003-ls-files-narrow-match.sh      |   39 ++++++
 t/t3003/1                             |    3 +
 t/t3003/12                            |    6 +
 t/t3003/clone-escape                  |    4 +
 t/t3003/cur-12                        |    2 +
 t/t3003/root-sub-1                    |    1 +
 t/t3003/slash-1                       |    1 +
 t/t3003/sub-1                         |    2 +
 t/t3003/sub-only                      |    3 +
 t/t3003/subsub-slash                  |    3 +
 t/t3004-ls-files-sparse.sh            |   40 ++++++
 t/t3004/cached.expected               |    5 +
 t/t3004/deleted.expected              |    1 +
 t/t3004/everything.expected           |   10 ++
 t/t3004/modified.expected             |    2 +
 t/t3004/no-checkout.expected          |    2 +
 t/t3004/orphaned-no-checkout.expected |    3 +
 t/t3004/orphaned.expected             |    1 +
 t/t3004/others.expected               |    2 +
 t/t3004/sparse-cached.expected        |    3 +
 t/t3004/sparse-everything.expected    |   11 ++
 t/t5703-clone-narrow.sh               |   39 ++++++
 test-index-version.c                  |   14 ++
 unpack-trees.c                        |  210 ++++++++++++++++++++++++++++++++-
 unpack-trees.h                        |   22 ++++
 wt-status.c                           |   39 ++++++
 wt-status.h                           |    1 +
 46 files changed, 1047 insertions(+), 50 deletions(-)
 create mode 100755 t/t2011-checkout-sparse.sh
 create mode 100755 t/t2104-update-index-no-checkout.sh
 create mode 100755 t/t3003-ls-files-narrow-match.sh
 create mode 100644 t/t3003/1
 create mode 100644 t/t3003/12
 create mode 100644 t/t3003/clone-escape
 create mode 100644 t/t3003/cur-12
 create mode 100644 t/t3003/root-sub-1
 create mode 100644 t/t3003/slash-1
 create mode 100644 t/t3003/sub
 create mode 100644 t/t3003/sub-1
 create mode 100644 t/t3003/sub-only
 create mode 100644 t/t3003/subsub-slash
 create mode 100755 t/t3004-ls-files-sparse.sh
 create mode 100644 t/t3004/cached.expected
 create mode 100644 t/t3004/deleted.expected
 create mode 100644 t/t3004/everything.expected
 create mode 100644 t/t3004/modified.expected
 create mode 100644 t/t3004/no-checkout.expected
 create mode 100644 t/t3004/orphaned-no-checkout.expected
 create mode 100644 t/t3004/orphaned.expected
 create mode 100644 t/t3004/others.expected
 create mode 100644 t/t3004/sparse-cached.expected
 create mode 100644 t/t3004/sparse-everything.expected
 create mode 100755 t/t5703-clone-narrow.sh
 create mode 100644 test-index-version.c