Hovercar Experiments

Physically simulated hovercars. Because hoverboards will never be enough. ------------------------ Update v18.2: - Added support for R15 avatars, cuz they look sweet - Small security update Previous Update: - Fixed the countdown timer UI showing up preemptively. Sometimes I want to hit myself. - Added some background ambience - Minor bugfixes Working on: - Redoing the whole thing because honestly, I can do better. I've learned a lot in making this, and I came to realize that I can make something much more interesting, intricate, and with code that I don't hate looking at as much. It'll take a while, but the plan is to have a Pod Racing-esque experience.