Add Curtains.js integration#28

Curtains.js is a lightweight vanilla WebGL javascript library that turns HTML DOM elements into interactive textured planes.

i think custom variable elemento woudl be more usefull. rightnow we cant anchor anything there are awesome js libs if we can get a vraiable output from the motion.page we can hook with anything we want. specialy for scroll trigger 3d animations. rightnow we can make scroll trigger 2d animations but we cant do 3d.