Add option for parallax soft shadows
Vtastek aka Dexter added iterative parallax mapping with soft shadows to his custom shaders. He favored this approach over other techniques such as Parallax Occlusion Mapping as it uses only 4 samples, has no artifacts at grazing angles, is fast, and can apply to any surface. As it is a straight up improvement to OpenMW's existing parallax as far as I can see, I think it should be part of OpenMW core shaders proper. Aside from improving the look of parallax mods for TES3, this would further enhance the parallax maps used extensively in TES4 environments.
A clip of the soft shadows in action: https://streamable.com/ahlgta