Hex's Default Shaders Rewrite

The shader was not fully rewrited, some functions are still here.

Updates GHub

• Separated Codes for Nether and Overworld (Custom code for end is coming.)
• Fixed Nether Ugly Fog.
• Rewrited Nether Saturation.
• Fixed skylight leak in nether.
• Trying to add Distant Horizons support...