Some way to allow overlapping animations

[jkomoros]

That is, animations that start not at the exact same time as the animation before, and not after the animation before has ended, but before they've ended.

This is a bit hard because we don't actually know when to expect the animations to have ended.

One way of doing it is basically having the animations have a delay of 0, but then have a manual delay after that that's some multiple of the --animation-length. So kind of a hybrid.

It's also very hard to accomplish because it assumes many animations happening at the same time to keep track of separately (eep!)

Related to #717, #716