Modernization and cleanliness tasks

[FranzPoize]

Build a list of modernization and cleanliness tasks for the prototypo apps:

• [x] Switch to webpack 2 and use performance hint and code splitting
• [x] Switch to yarn
• [ ] Find ways to reliably test the app
• [ ] Find ways to reliably test the worker
• [ ] Find ways to prevent bad font computation to avoid worker crash
• [ ] Make the worker relaunchable by making it more stateless
• [x] remove paper
• [ ] use a more functional opentype.js

[FranzPoize]

Ideas and comments welcome.