Add a GUI to diceware

[drebs]

Hello,! I think a GUI would increase usage of diceware among less tech savvy users, and could help increase the overall security of passphrases people have to remember.

This is a list of features I thought about (not necessarily implemented in this order):

• A text box that displays the generated passphrase.
• A button to generate a new passphrase.
• Fields for each configurable parameter (number of words, capitalize, number of special characters, choice of delimiter, word list to use, source of randomness plus a special field for inputting real dice values, if that is the case).
• A button to save defaults.
• An entry in the applications menu.

@ulif, do you think this could be added to this repository and be distributed in the same Python package? Or does it make sense to separate it somehow?

Another question I have is which graphical library to use. Some criteria I thought for choosing are the least amount of dependencies, availability in most distributions, and maintainability in the long run.

Any thoughts are appreciated, and I'd be willing to contribute code for this if you think it's a good idea.