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

builtin/am.c

@@ -34,6 +34,7 @@
 #include "string-list.h"
 #include "packfile.h"
 #include "repository.h"
+#include "pretty.h"
 
 /**
  * Returns the length of the first line of msg.