Adds a data-composite option and fixes paths for effects. Otherwise
just applies the same conversion as already applied to demos, sometimes
moving a <style> element to the right place.
1. Introduces a set of helper methods to easily create and define new effects.
2. Uses clip animations and placeholders instead of wrappers for clip effects.
3. Ensures all animations are detectable as animated
Fixes#10599Fixes#9477Fixes#9257Fixes#9066Fixes#8867Fixes#8671Fixes#8505Fixes#7885Fixes#7041
Closes gh-1017
