Integrate freeman lab dependency, upgrade regl to v2.0

[`freeman-lab/pixel-grid`](https://github.com/freeman-lab/pixel-grid) uses [`regl`](https://github.com/regl-project/regl) version [`^0.11.0`](https://github.com/freeman-lab/pixel-grid/blob/master/package.json#L38)

It works fine. 

It would be nice to hardcode the barebones of `freeman-lab/pixel-grid` into this package, and try upgrading to regl 2.0 if there's any perf/security benefits.