fix local browsing in Fx, change to jsDelivr CDN

missing `http:` breaks local files browsing in Fx
Changed CDNs to jsDelivr; same [network + CloudFlare], 1 less DNS lookup, added auto minor revision [upgrades alias](https://github.com/jsdelivr/jsdelivr#version-aliasing)
This one definitely can be switched to `https://`... I agree with leaving the rest of them agnostic