Another array assignment instead of pushing
Move callback out of function so it isn't redeclared each time
Produce a flat array instead of an array of arrays.

Originally the set looked like: [[1,2,3],[1,2,3],...]

Now the set produced looks like: [1,2,3,1,2,3,...]

This improves performance, and it also aligns better with
drawing image data to a <canvas>. ImageData `data` is a
flat array, which means drawing operations now only require one
loop instead of a nested loop.
Version bump
In demo, wrap canvas update call in an RAF