Initial try for making amp toggable

[ghost]

This is a very early try, and obviously not optimal. Bug I found after some quick testing: the extension defaults to "off" ~~and it does that every single time the url changes, so you have to manually enable it every time you click a link~~ it's weirder than that. I think defaulting it to "on" might be better but I wanted to get this out there, so here it is.

[bquast]

could this be changed to default on so that we can experiment with it?