Split questions out of exercise content into en_question_bank.json, which are referenced by smyth keys.
Cleaned up implementation of handwritten slide insertion.
Info slides load async just like all other exercises.
Added Questions and Tasks fields to Utils.
Slides marked up with smyth references get auto-populated with task-based questions.
Questions in the question bank use Underscore templating to make embedding information from the
retrieved words into the question easier.
Made home, lesson screens, and individual modules logged-in only (so people are answering questions while logged in).
Updates to final slide, so it shows a few stats about your accuracy and time on that module.
Added styling and whatnot.