Open control on start and provide popups
Hello. I've been looking at the comments on this thread and found some features that I wanted to add.
This PR will open the layer control on load provided no layers have already been loaded and also opens two popups explaining how to select layers.

@kevinzluo ...so coool 🎉 !
I see there is a gif added in the PR , can you upload that gif somewhere and give the link to the url and remove the gif from the PR . Thanks !
Sure thing!
I have switched it now 😄 .
@kevinzluo please resolve conflicts so that @sagarpreet-chadha can give his final review. Thanks!
There will be merge conflicts after #104 is merged. Please merge that one first and then I will fix the conflicts here.
Hi! This is really awesome!
Is this something we could integrate into the main codebase, do you think, rather than in an independent index.js file?
I'm sorry it took me so long to respond!!!