Merge pull request #450 from mozilla/enhancement/locomotion

README.md

src/hub.js

src/systems/tunnel-effect.js

src/utils/postprocessing/EffectComposer.js

src/utils/postprocessing/MaskPass.js

src/utils/postprocessing/README.md

src/utils/postprocessing/RenderPass.js

src/utils/postprocessing/ShaderPass.js

src/utils/shaders/CopyShader.js

src/utils/shaders/README.md

src/utils/shaders/VignetteShader.js