Add stack.gl and use gslify etc. to execute shaders for the ProcGen pipeline

[lemilonkh]

See the following:

• http://stack.gl/
• http://stack.gl/#learning
• https://github.com/stackgl/glslify
• http://hughsk.io/voxel-fall/
• http://mikolalysenko.github.io/gif-3d/?href=example/banana.gif
• https://github.com/mikolalysenko/voxel-mipmap-demo/

[lemilonkh]

https://github.com/stackgl/glsl-lighting-walkthrough https://medium.com/@Max_Goldstein/the-tools-for-interactive-visual-things-on-the-web-6e90f07c9c72