Weather tracking issue

A simplistic weather system has been merged with !3183 (merged).

Currently the weather is controlled by noise on the server.

Tasks:

• Weather sim with cellular automata, I have experemented with this here
• Integrate interactions with weather for other systems. How it should interacts needs to be discussed
  • Agents
  • Temperature system
  • Entity spawning
• Visuals in voxygen for other weathers than rain and clouds
  • Snow
  • Thunder/Lightning (!3464 (merged))
  • Sandstorms
• Look into moving auroras to the weather system, so it could be used for Frostgigas spawning/ai.
• Draw rain motion blur direction relative to camera's velocity.
• Ocean waves, which would be part of the weather system, so that the waves could have an impact on physics.
• Server optimizations, probably needs to be done for larger world sizes, or if we want smaller weather cells.
  • Run the simulation asynchronously instead of directly in the ecs system.
  • Spread out sending weather updates over multiple ticks instead of sending to all clients in one tick.
• Possible voxygen optimizations
  • Lerp between two weather states on the gpu instead of cpu.
  • Sample texture instead of noise when drawing rain.
• Fix issue in voxygen with rain occlusion matrix being nan when looking straight up, probably related to #1332