Test GIF

It's working decently well for version 1. One thing that could be
improved is the lines get noticeably thicker as the image zooms in.
That's due to the interpolation, so maybe there's different
interpolation parameters I can look into. Otherwise, to get really crisp
geometric zooms, I'll have to check into GIMP's vector graphics
capabilities (or implement some myself). The current script should be ok
for general images, though, although for now the initial image must
already be fractal - the script doesn't create the zoomed in sub-images
automatically (yet).