Added shader, model selector dropdown, obj2js converter, triangle counter etc

[fyyyyy]

• Model Selector
• More 3D models
• obj model converter
• Shader (adapted from https://github.com/ilia3101/Javascript-3D-Renderer/)
• Controls
• and more ...

Probably makes no sense to merge, so here's a fork
https://github.com/fyyyyy/formula#

Includes #4 and #2

[fyyyyy]

Added a button to load obj files directly in the browser