Add post processing framework based on three.js passes

[arose]

interesting post processing passes include

• [ ] cel shading/edge detection/highlight
• [x] antialiasing (taa, msaa, smaa)
• [ ] ssao
• [ ] vignetting
• [ ] depth of field

[arose]

Antialiasing available in dev branch (by default an antialiased image is rendered on standstill). Next up cel shading.