*** Submitted as
https://code.google.com/p/go/source/detail?r=df1405f02219 ***
crypto/des: add an example to demonstrate EDE2 operation.
EDE2 is a rare DES mode that can be implemented with crypto/des, but
it's somewhat non-obvious so this CL adds an example of doing so.
Fixes issue 3537.
R=golang-dev, adg
CC=golang-dev
https://codereview.appspot.com/6721056
https://codereview.appspot.com/6721056/
