Use localStorage to store user defined datas

[ffoodd]

Letting users define datas through a simple HTML form, we should be able to store values in localStorage.

I’d love to find a way to directly write datas to a JSON file, too…

Sources:

• Update CSS custom properties with JS, listening to form inputs by Wes Bos;
• localStorage on MDN
• Live Interface Theming by Jonathan Harrel

Usages:

• Theming, obviously;
• Data customization: grid positions (like for maps, wedding's seating plan, etc.), card values (like in planning poker cards, or card sorting datas)…

Should be reusable and pretty fun to do :)

[ffoodd]

Also take a look at FormData on MDN.

[ffoodd]

Relates to #47 .