First spray renderer prototype

This is my first shot at spray simulation on the GPU.

Spray patterns are based on the textureless simplex noise function from https://github.com/ashima/webgl-noise

The trail uses PROCESSING_POINT_SHADER

TODO:
- Extrapolate to fill the gaps between points
- Implement stretching based on the angle of incidence
- Implement dynamic distribution (texture based for starters)
- Smooth the stroke
- Add procedural drips
- Add sprite-based splats (?)
- ...