SF patch 876130:  add C API to datetime module, from Anthony Tuininga.
The LaTeX is untested (well, so is the new API, for that matter).
Note that I also changed NULL to get spelled consistently in concrete.tex.
If that was a wrong thing to do, Fred should yell at me.
diff --git a/Misc/NEWS b/Misc/NEWS
index f2b65e6..b5038f7 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -559,6 +559,10 @@
 C API
 -----
 
+- Thanks to Anthony Tuininga, the datetime module now supplies a C API
+  containing type-check macros and constructors.  See new docs in the
+  Python/C API Reference Manual for details.
+
 - Private function _PyTime_DoubleToTimet added, to convert a Python
   timestamp (C double) to platform time_t with some out-of-bounds
   checking.  Declared in new header file timefuncs.h.  It would be