Support for PKINIT on Windows now available in MIT Kerberos

[Ken Hornstein]

(Since a few people have asked about this over the years, I felt it was
worth an announcement).

I am pleased to report that MIT Kerberos now supports PKINIT on the
Windows platform.  The technical details of this can be found in the
pull request here:

	https://github.com/krb5/krb5/pull/1401

This means that with a PKCS#11 library and the appropriate client
configuration one can use a smartcard to authenticate with MIT Kerberos.
I have tested this support with a PIV card and both the OpenSC and
ActivClient PKCS#11 libraries.

Right now this support is only on the 'master' branch of MIT Kerberos
and you will have to build MIT Kerberos from source to utilize it;
the build directions are in the source tree under src/windows/README.

Thanks to Greg Hudson working with me to push this across the finish line.

--Ken