Refactor Javascript In Preparation for Multiple Wordlists

[dmuth]

There's been some talk about multiple word lists, and as part of the effort for this, I think I'm going to need to do a refactor of Javascript, as src/index.js is currently at 500 lines. So here's the stuff I want to get done in this branch:

• Split up Diceware.go() into smaller functions
• Put display_row() and rollDiceHandler*() functions into a separate file
• Loading file code
  • I want to change this or it's just an AJAX/XHR load request
  • ...and the file should be a plain file
• Upload Roll Dice! button to display that the wordlist is being loaded. This should prevent conditions where people click the button before the wordlist is loaded.
• Add <NOSCRIPT> tags for the benefit of people using Tor or a similarly locked down browser

At the conclusion of this bug, I should be in a much better state to be able to start loading additional wordlists, if so desired. I'm specifically keeping #45 and #39 in mind here.

NOTE: One thing that hampers me is that I I don't do much front-end development professionally, so my knowledge of the Javascript ecosystem (like, webpack and friends) has stagnated. Any guidance for structuring my code better is certainly welcome. :-)

-- Doug