v0.10

#36 Don't schedule a requestAnimationFrame if there is nothing to animate
#37 Return a promise when an confetti batch completes animating
#38 Correctly position confetti source when confetti added immediately after instantiation
#39 clean up shapes every 10 not 100 iterations
#40 add docs about addConfetti promise to README.md

Huge thanks to @grork for contributing to this library! 🚀