Cautious introduction of a patch that started from
SF 560379:  Karatsuba multiplication.
Lots of things were changed from that.  This needs a lot more testing,
for correctness and speed, the latter especially when bit lengths are
unbalanced.  For now, the Karatsuba code gets invoked if and only if
envar KARAT exists.
diff --git a/Misc/ACKS b/Misc/ACKS
index c7d173b..a1054f6 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -106,6 +106,7 @@
 Steve Cousins
 Alex Coventry
 Matthew Dixon Cowles
+Christopher A. Craig
 Drew Csillag
 Tom Culliton
 John Cugini