Added position as out variable from vertex shader.

Adding the position out form vertex shader makes us skip computation of position in the fragment shader based on gl_FragCoord.

Add No-Brain Jogging to examples

standardized glsl variable naming

implemented custom fragment shader support

add a guide for making scenes

fix typo for matrix

CI support for example/amidakuji

Adds video mode support and a community example for its usage.

readme: remove tracking from Gitter URL

contributing: remove tracking from link to Gitter