Merge branch 'cr/reset'

* cr/reset:
Simplify cache API
An additional test for "git-reset -- path"
Make "git reset" a builtin.
Move make_cache_entry() from merge-recursive.c into read-cache.c
Add tests for documented features of "git reset".

diff --cc Makefile
Simple merge

diff --cc builtin-add.c
Simple merge

diff --cc builtin-apply.c
Simple merge