Merge branch 'lt/in-core-index'

* lt/in-core-index:
lazy index hashing
Create pathname-based hash-table lookup into index
read-cache.c: introduce is_racy_timestamp() helper
read-cache.c: fix a couple more CE_REMOVE conversion
Also use unpack_trees() in do_diff_cache()
Make run_diff_index() use unpack_trees(), not read_tree()
Avoid running lstat(2) on the same cache entry.
index: be careful when handling long names
Make on-disk index representation separate from in-core one

diff --cc builtin-apply.c
Simple merge

diff --cc builtin-commit.c
Simple merge

diff --cc builtin-fsck.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc diff.c
Simple merge

diff --cc merge-recursive.c
Simple merge

diff --cc t/t0000-basic.sh
Simple merge

diff --cc wt-status.c
Simple merge