Prismarine Shader

1) Removed underwater light flickering and add overall light flickering. Affects blocklight, sunlight and volumetric fog/rays.

2) Added lots and lots of new configs such as fog color, sky color, distant fade color, etc.

3) Tweaked clouds once again. For now I'm fully happy with the result I have.

4) Modified underwater lighting. 5) Stars are now always visible.

6) Added stars to The End.

7) Tweaked volumetric fog and lowered the default persistence of volumetric rays.

8) Fixed distant fade not working properly and turned it on by default.

9) Added distant fade to The End and Nether.

10) Added blocks from 1.17 (BSL)

11) Removed custom sky from PhysicalSL. Can be toggled by editing shader's code but it isn't present in game anymore.

12) A lot of small tweaks and improvements, too lazy to describe them.