Allow custom wordlists to be used

[majjoha]

Apart from the wordlist already in the repository, EFF also lists additional wordlists here and here. There is, currently, no functionality for handling custom wordlists, but it would be a useful feature to add.

For instance, in the following manner:

% stack exec -- passphrase short-wordlist.txt

By default, it should use the wordlist already shipped with the app, but if a path to a file is provided, it should read this file instead and, of course, fail gracefully in case the file does not exist or follow the expected format.

[sshine]

Hi :) Can I grab this? (My git repository spilled the beans.)

[majjoha]

Absolutely. Thanks! I'll let you know when I've had a chance to look at your pull request.