Stabilising a video around an object using Natron's tracker node

An example of how you can use [Natron](https://natrongithub.github.io/)'s tracker node to stabilise a video around a moving and spinning object. Goes with the article on the matter I wrote for [Linux Magazine #220](https://www.linux-magazine.com/Issues/2019/220/Tutorials-Natron/(offset)/3).