Publish as ECMAScript module

[daniel-sc]

For optimal bundle size/tree shaking it would be good if this package could be published as ECMAScript module (instead of CommonJS).

As this lib targets performance optimization, I'd fit well to take care of bundle sizes as well ;)

See e.g. https://angular.io/guide/build#configuring-commonjs-dependencies

[mattbishop]

👍 It doesn't import into ESM modules very well, need to do this:

import {iterate} from "iterare"
import {IteratorWithOperators} from "iterare/lib/iterate.js"
import {isIterable} from "iterare/lib/utils.js"