natural-mystic-shaders-1.8.0

The 1.16.0 nether upgrade surprisingly didn't break my shaders too
much so this is only a small fix and an improvement.

• Updated the base code from 1.9.0 to 1.16.0.

• Fixed an issue with Minecraft Bedrock 1.16.0: Water in a swampland
  was sometimes not detected and was rendered in the vanilla way.
• Added a configuration item ENABLE_FANCY_WATER which is enabled
  by default. Now you can leave water unmodified by the shader if you
  wish.