Solas Shader

Features added/changed:

+ Reworked the entire night sky. Greatly improved generated nebulae, improved the color palette and increased stars amount.
+ Reworked Nether smoke. Improved its shaping, noise sampling and visibility.
+ Added several new options in config menu, including constant aurora visibility and generated nebula config.
+ 
+ Small adjustments to clouds. Their amount slightly decreases at night to provide better visibility of the night sky.
+ Improved exponetial fog behaviour.

Features fixed:

+ Fixed Voxy water clipping through LODs
+ Fixed exponential fog being almost invisible with Voxy
+ Fixed broken reflections with Distant Horizons (PR by TillSilph)
+ Fixed incorrect sky darkening when underground (PR by marktible)
+ Fixed SSR breaking water normals in certain conditions (PR by marktible)