Show Nim: Boxy, 2D GPU rendering with a tiling atlas and Pixie

[treeform]

@jorjun_arch, Boxy does not make gifs. How are you producing the animation? If 
you already have animation images if have used ffmeg in the past: 
<https://ottverse.com/how-to-create-gif-from-images-using-ffmpeg>/ If you need 
to make image sequence then probably some thing like 
<https://github.com/treeform/pixie> if they need to be vector in nature. If you 
just want to record your game or app thing then <https://getsharex.com>/ is 
pretty good.