This was done to make reviewing easier, again because it is virtually impossible to search for the operators in the code.
Going through this revealed quite a few places where texture animations were on but shouldn't and even more places that did not check PASLVERS, although they were preparing some paletted rendering.
This will now both exclude floor caps when only ceiling elements are used and everything outside the bounding box of active portal lines.
Hopefully this is enough to fix the issues with portal caps but of course it is not foolproof if someone just makes the right setup.
- move a few variables from SceneDrawer to FRenderViewpoint.
The global r_viewpoint variable is left alone now to always represent the current viewpoint to the play code.
The main reason behind this change is to reduce the amount of global variables being used by the hardware renderer's scene processing code.