Some JS refactoring

[batpad]

Am making this ticket just to open the discussion, so I don't feel terrible implementing new features on top of the current structure.

I think my idea would be to:

• Make an index.js and move that out of index.html
• Use Javascript imports to import / export modules and keep things in separate files

I think with this light restructure, we can begin to start logically grouping the code a bit better, and still stay away from using a full-blown framework or any build process.

@pratapvardhan let know if you have any opinions on how we should structure this. Am happy to do this light touch refactor at some point, happy to add to the mess a bit for now :-) cc @planemad

[pratapvardhan]

No strong opinions. I'm thinking moving to ES modules is great, moving to /js folder might be good?

/js
 - featureControl.js
 - ..
 - utils.js
 - index.js