[Ml-yokadi] New feature : encryption

[Sébastien Renard]

Hello,

On the "crypt" branch you'll find a new feature for yokadi : encryption. You 
can encrypt task title (I plan to add encryption on task description soon).

Encryption is done in a symmetric way with GnuPG.

An encrypted task title can be created with t_add -c

By default, encrypted data are not displayed. If t_list -c is used, yokadi try 
to decrypt data and ask passphrase if needed.

It needs some polishing and security review (for instance, history contains 
clear text.... needs to be rewritten).

Classic use case is when storing password or other important stuff in yokadi. 
If you always kept your yokadi database on your $HOME, you can rely on Unix 
security, but if you backup your db or have it on usb stick (or if you are 
paranoiac !) it can be handy.


Please, give me feedback about that.

-- 
Sébastien