Snow and rain VFX move with the player

In OpenMW the snow effect moves with the players view, which gives it a cheap overlay look, see video for comparison with vanilla Morrowind:

https://www.youtube.com/watch?v=Yt37MAQ0CfQ

Steps to reproduce:

1. changeweather [YourRegion] 8
2. Observe

OpenMW version: 0.36.1

Note: The snow in OpenMW also sometimes has kind of a patchy look, which can be seen in the video too

(RM-2698 from redmine: created on 2015-06-17 by Thomas Staudinger, , closed on 2017-10-15 by Miloslav Číž, relates #3404, duplicates #3536 (closed))