react-move-scatter: implement rolling override of `timing` and `events` in animate.js.
react-move-scatter: implement rolling override of `timing` and `events` in animate.js.

- Previously, I had only had the function override the very root (animate.timing, animate.events), with the return values of the most specific animate functions (animate[animatableProp].update => { timing, events }.
- Now, the root definitions can still be overridden by the user, but the intermediate value within a prop can specify its `timing` and/or `events`.
- For example a `fill` property can have its `timing` attribute modified on `update` by:
  - animate.timing // user's most root `timing`
  - animate.fill.timing // root can be overridden by the `timing` property of `animate.fill`
  - animate.fill.update => ({ timing }) // will override all other `timing` definitions.

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