* Mostly tightening up the details on the hkp4py example script.
* Also fixed a typo in the LGPL boiler plate text included in all the
other example scripts for the HOWTO.
* Updated the decryption example code in the HOWTO and the
corresponding decrypt-file.py script to gracefully handle a
decryption failure. This error will always be triggered when GPGME
is used to try to decrypt an old, MDC-less encrypted message or
file.
