Animations could potentially crash due to removing or adding listeners during playback. Instead of a complex queue system I opted to just throw exceptions if changes are made during playback.
Merge pull request #597 from ToxicBakery/animation-rewrite

Animations could potentially crash due to removing or adding listeners during playback.
Merge commit '4d5743657024f6ed7f9a6f29bf0532638d1490f3' into task-queue-dev