Issue #2819: Add math.sum, a function that sums a sequence of floats
efficiently but with no intermediate loss of precision.  Based on
Raymond Hettinger's ASPN recipe.  Thanks Jean Brouwers for the patch.
diff --git a/Misc/NEWS b/Misc/NEWS
index b7b8685..9479125 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -36,6 +36,9 @@
 Extension Modules
 -----------------
 
+- Issue #2819: add full-precision summation function to math module,
+  based on Hettinger's ASPN Python Cookbook recipe.
+
 - Issue #2592: delegate nb_index and the floor/truediv slots in
   weakref.proxy.