Merge branch 'kh/commit' into wc/add-i

Merge branch 'kh/commit' into wc/add-i

This is to use a few functions refactored to use in the built-in
commit series.

* kh/commit: (28 commits)
  Add a few more tests for git-commit
  builtin-commit: Include the diff in the commit message when verbose.
  builtin-commit: fix partial-commit support
  Fix add_files_to_cache() to take pathspec, not user specified list of files
  Export three helper functions from ls-files
  builtin-commit: run commit-msg hook with correct message file
  builtin-commit: do not color status output shown in the message template
  file_exists(): dangling symlinks do exist
  Replace "runstatus" with "status" in the tests
  t7501-commit: Add test for git commit <file> with dirty index.
  builtin-commit: Clean up an unused variable and a debug fprintf().
  Call refresh_cache() when updating the user index for --only commits.
  builtin-commit: Add newline when showing which commit was created
  builtin-commit: resurrect behavior for multiple -m options
  builtin-commit --s: add a newline if the last line was not a S-o-b
  builtin-commit: fix --signoff
  git status: show relative paths when run in a subdirectory
  builtin-commit: Refresh cache after adding files.
  builtin-commit: fix reflog message generation
  launch_editor(): read the file, even when EDITOR=:
  ...