Stretch and Squash Bounce Animation

[lucymhdavies]

Bounces at the moment are a little flat

Add some stretch and squash

https://blog.animationmentor.com/squash-and-stretch-the-12-basic-principles-of-animation/

Possibly warrants a standalone experiment https://github.com/lucymhdavies/go-experiments

Unsure yet whether this should be applied to the egg before or after the eyes are drawn on.

[lucymhdavies]

I found someone who implemented Squash and Stretch in CSS. https://codepen.io/milberferreira/pen/RKVWyg

I've tweaked theirs slightly, to come up with this: https://codepen.io/anon/pen/QPxYpG

How I'm gonna implement this in Go, I'm not sure, but that's the effect I'm going for.

(only the body should undergo stretching/squashing. the eyes should remain normal)