[GSoC][PATCH v7 00/26] Convert "git stash" to C builtin

Hello,

Here is the whole `git stash` C version. Some of the previous patches were already reviewed (up to and including "stash: convert store to builtin"), but there are some which were not (starting with "stash: convert create to builtin").

In order to see the difference between the shell version and the C version, I ran `time` on:

* git test suite (t3903-stash.sh, t3904-stash-patch.sh,
t3905-stash-include-untracked.sh and t3906-stash-submodule.sh)

        t3903-stash.sh:
        ** SHELL: 12,69s user 9,95s system 109% cpu 20,730 total
        **     C:  2,67s user 2,84s system 105% cpu  5,206 total

        t3904-stash-patch.sh:
        ** SHELL: 1,43s user 0,94s system 106% cpu 2,242 total
        **     C: 1,01s user 0,58s system 104% cpu 1,530 total

        t3905-stash-include-untracked.sh
        ** SHELL: 2,22s user 1,73s system 110% cpu 3,569 total
        **     C: 0,59s user 0,57s system 106% cpu 1,085 total

        t3906-stash-submodule.sh
        ** SHELL: 2,89s user 2,99s system 106% cpu 5,527 total
        **     C: 2,21s user 2,61s system 105% cpu 4,568 total

        TOTAL:
        ** SHELL: 19.23s user 15.61s system
        **     C:  6.48s user  6.60s system

* a git repository with 4000 files: 1000 not changed,
1000 staged files, 1000 unstaged files, 1000 untracked.
In this case I ran some of the most used commands:

        git stash push:

        ** SHELL: 0,12s user 0,21s system 101% cpu 0,329 total
        **     C: 0,06s user 0,13s system 105% cpu 0,185 total

        git stash push -u:

        ** SHELL: 0,18s user 0,27s system  108% cpu 0,401 total
        **     C: 0,09s user 0,19s system  103% cpu 0,267 total

        git stash pop:

        ** SHELL: 0,16s user 0,26s system 103% cpu 0,399 total
        **     C: 0,13s user 0,19s system 102% cpu 0,308 total

Best regards, Paul Ungureanu

Joel Teichroeb (5):
  stash: improve option parsing test coverage
  stash: convert apply to builtin
  stash: convert drop and clear to builtin
  stash: convert branch to builtin
  stash: convert pop to builtin

Paul-Sebastian Ungureanu (21):
  sha1-name.c: added 'get_oidf', which acts like 'get_oid'
  stash: update test cases conform to coding guidelines
  stash: renamed test cases to be more descriptive
  stash: implement the "list" command in the builtin
  stash: convert show to builtin
  stash: change `git stash show` usage text and documentation
  stash: refactor `show_stash()` to use the diff API
  stash: update `git stash show` documentation
  stash: convert store to builtin
  stash: convert create to builtin
  stash: replace spawning a "read-tree" process
  stash: avoid spawning a "diff-index" process
  stash: convert push to builtin
  stash: make push to be quiet
  stash: add tests for `git stash push -q`
  stash: replace spawning `git ls-files` child process
  stash: convert save to builtin
  stash: convert `stash--helper.c` into `stash.c`
  stash: optimize `get_untracked_files()` and `check_changes()`
  stash: replace all `write-tree` child processes with API calls
  stash: replace all "git apply" child processes with API calls

 Documentation/git-stash.txt |    7 +-
 Makefile                    |    2 +-
 builtin.h                   |    1 +
 builtin/stash.c             | 1562 +++++++++++++++++++++++++++++++++++
 cache.h                     |    1 +
 git-stash.sh                |  752 -----------------
 git.c                       |    1 +
 sha1-name.c                 |   19 +
 t/t3903-stash.sh            |  190 +++--
 9 files changed, 1714 insertions(+), 821 deletions(-)
 create mode 100644 builtin/stash.c
 delete mode 100755 git-stash.sh