Add in the ability to use the pre-1.11 end portal parallax / Add the ability to toggle end portal overlay

[MerpisMe]

Simply put, I'd love to be able to use the old parallax effect that the starfield would use rather than the locked screenspace effect. The older one was much prettier. Additionally, it'd also be nice if there was an ability to, like the nether portal, have the end portal effect overlaid onto the portal view, and even potentially use a similar or identical effect to the pre-1.11 end portal.