Merge branch 'ab/date-mode-release'

Plug (some) memory leaks around parse_date_format().

* ab/date-mode-release:
  date API: add and use a date_mode_release()
  date API: add basic API docs
  date API: provide and use a DATE_MODE_INIT
  date API: create a date.h, split from cache.h
  cache.h: remove always unused show_date_human() declaration

diff --cc builtin/am.c
Simple merge

diff --cc builtin/commit.c
Simple merge

diff --cc cache.h
Simple merge

diff --cc config.c
Simple merge

diff --cc object-name.c
Simple merge

diff --cc refs.c
Simple merge