Log Message:
Update digest to version 20160216, as proposed on tech-pkg.

Changes since previous version:

+ add Taylor Campbell's implementation of SHA3 digests.  This includes
code to calculate 224, 256, 384 and 512bit length digests.

+ change the license on all the code I wrote to be 2-clause BSD

+ modify license years for things that have been changed

+ add self-test command line option to digest(1) via the -t switch

pkgsrc changes

+ derive version number for the package automatically from the source
code