Attempt to create a basic 2d physics engine in go for futur games.
Inspired if not copied from https://gamedevelopment.tutsplus.com/tutorials/how-to-create-a-custom-2d-physics-engine-the-basics-and-impulse-resolution--gamedev-6331 and https://github.com/vonWolfehaus/von-physics/blob/master/src/physics/Physics2.js