Simple esm dist output

[trusktr]

Fixes #2

The commits have all the details. TLDR: simple ESM output compatible with most tools of today, type definitions just work.

Breaking change:

import {w} from 'wazum' // before
import * as w from 'wazum' // now

This can be tested by installing my fork from git:

npm install 'wazum@trusktr/wazum#simple-esm-dist-output'

Note that the new prepare script added to package.json is what allows install from git to be possible (when using npm). Npm will install devDependencies locally, run the prepare script, then package the library after the prepare script has finished. Note that this may not work with yarn or pnpm because they don't follow (last I checked) this part of NPM spec.