Replaces more and more of the web until you realize that this is not the true reality, and also that there is no truth.
We'd put this on the firefox store, but that requires a real person to vet it first, and I'm not 100% sure they'd allow this in their hallowed repository, so we're stuck with manual installation now.
Basically, install jpm, then cd to this directory and run jpm xpi, then install it in your running firefox with Ctrl+O. More clarification here.