Reasoning:
* They're horribly broken (they completely ignore slopes).
* A similar final demo GL-only feature (coronas) has been completely disabled.
* Nobody's going to bugfix them before release because not even the devteam's resident GL users use them.
* They look ugly.
* Like Kart, remove cv_precipdensity.
* Like Kart, replace "Infinite" draw distance value with "None".
* Better thinker with more return optimisation.
* Better placement of thinking in rendering, to avoid ceiling-mounted sprite glitches.
The skybox rendering process has been replaced with portals instead. Those are generated after the first BSP tree pass by looking for existing sky visplanes at the time, and their windows are used to define new portals.
The skybox portals are still incomplete and cause visual glitches when masked elements are involved.
