#4 GnuPG integration

[Simon Hay]

- Have 'Sign' and 'Encrypt' tick boxes in compose
window, and a setup field into which you can paste your
keys.

- Automatically encrypt a copy of each message for
yourself when stored in Sent folder.

- Automatically check signatures of any signed messages
received; have a field to store keys in Contacts.

- Remember passphrase for this session once it's been
entered, or until 'forget' button is pushed?