Merge branch 'nd/no-the-index'

The more library-ish parts of the codebase learned to work on the
in-core index-state instance that is passed in by their callers,
instead of always working on the singleton "the_index" instance.

* nd/no-the-index: (24 commits)
blame.c: remove implicit dependency on the_index
apply.c: remove implicit dependency on the_index
apply.c: make init_apply_state() take a struct repository
apply.c: pass struct apply_state to more functions
resolve-undo.c: use the right index instead of the_index
archive-*.c: use the right repository
archive.c: avoid access to the_index
grep: use the right index instead of the_index
attr: remove index from git_attr_set_direction()
entry.c: use the right index instead of the_index
submodule.c: use the right index instead of the_index
pathspec.c: use the right index instead of the_index
unpack-trees: avoid the_index in verify_absent()
unpack-trees: convert clear_ce_flags* to avoid the_index
unpack-trees: don't shadow global var the_index
unpack-trees: add a note about path invalidation
unpack-trees: remove 'extern' on function declaration
ls-files: correct index argument to get_convert_attr_ascii()
preload-index.c: use the right index instead of the_index
dir.c: remove an implicit dependency on the_index in pathspec code
...

diff --cc archive-tar.c
Simple merge

diff --cc archive-zip.c
Simple merge

diff --cc builtin/add.c
Simple merge

diff --cc builtin/blame.c
Simple merge

diff --cc builtin/cat-file.c
Simple merge

diff --cc builtin/checkout.c
Simple merge

diff --cc builtin/commit.c
Simple merge

diff --cc builtin/grep.c
Simple merge

diff --cc builtin/pack-objects.c
Simple merge

diff --cc builtin/rm.c
Simple merge

diff --cc builtin/update-index.c
Simple merge

diff --cc convert.c
Simple merge

diff --cc diff.c
Simple merge

diff --cc dir.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc read-cache.c
Simple merge

diff --cc sequencer.c
Simple merge

diff --cc sha1-file.c
Simple merge