Create walkthrough

[IanMayo]

I'd like to train new users in how to use the app via a walkthrough.

1. consider react walkthrough libraries. the must meet these requirements
   a. allows focus on specific component, by putting mask across rest.of UI
   b. can trigger UI interactions, such as clicking on button, or entering text
   c. cam allow user to interact with app, and only move forward once a specific interaction has happened
2. introduce new walkthrough library
3. produce document containing processes for the user to learn, and components to learn about
4. implement walkthrough, starting at welcome page
5. add Help button to welcome page, to trigger walkthrough.
6. show walkthrough for new users
7. store cookie after walkthrough is closed. This prevents it opening next time.