v2.9.15

Fix zombie nodes (#120) and increase test stability

This release fixes the often-reported issue with zombie nodes staying after fast toggling. Huge thanks to @tobilen for tackling this problem!!

This release also includes some improvements to our tests, by polyfilling requestAnimationFrame. Huge thanks to @Hypnosphi for their work on this, and for everything they've done and continue to do for this project :D