use stronger hashes by default in enigmail
Inspired by http://keyring.debian.org/creating-key.html.
Please add the following options to extensions.enigmail.agentAdditionalParam.
personal-digest-preferences SHA512
cert-digest-algo SHA512
default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 ZLIB BZIP2 ZIP Uncompressed