Pimp the docs linter (and assorted changes) (#2553)

### Pimp the docs linter (and assorted changes)

 #### `scripts/lint-docs.js`

- Add an optional cache for faster runs
- Add a final report
- Don't return anything from `exec()`
- Cover more files

 #### `scripts/_command.js`

- Look for a "--cache" option

 #### `package.json` scripts

- Added `watch:lint-docs`
- Added `cleanup:lint` to remove the eslint and lint-docs cache files
- Changed `lint:docs` to use the `--cache` option
- Added `test:js` so that we can run the test suite without the linter
- Changed `test` to defer to `test:js`

 #### Actual lint fixes:

- Bad link in a migration guide
- The unicode dashes in the "https://en.wikipedia.org/wiki/Subject–verb–object" are not escaped by marked

### Some more lint-docs pimping

#### `scripts/lint-docs.js`

- some code reorg and cleanup (take a hint from the local coding conventions)
- fix misc bugs
- pass a User-Agent header to the requests
- even nicer reporting

#### `package.json`

- bump the @babel/parser dep to the latest

#### Docs

- tweaks based on lints missed due to previous bugs

### Docs: use the github page for velocity.js, the home page has too many errors.

Co-Authored-By: Isiah Meadows <contact@isiahmeadows.com>

docs/animation.md

@@ -9,7 +9,7 @@
 
 ### Technology choices
 
-Animations are often used to make applications come alive. Nowadays, browsers have good support for CSS animations, and there are [various](https://greensock.com/gsap) [libraries](https://velocityjs.org/) that provide fast JavaScript-based animations. There's also an upcoming [Web API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API) and a [polyfill](https://github.com/web-animations/web-animations-js) if you like living on the bleeding edge.
+Animations are often used to make applications come alive. Nowadays, browsers have good support for CSS animations, and there are [various](https://greensock.com/gsap) [libraries](https://github.com/julianshapiro/velocity) that provide fast JavaScript-based animations. There's also an upcoming [Web API](https://developer.mozilla.org/en-US/docs/Web/API/Web_Animations_API/Using_the_Web_Animations_API) and a [polyfill](https://github.com/web-animations/web-animations-js) if you like living on the bleeding edge.
 
 Mithril does not provide any animation APIs per se, since these other options are more than sufficient to achieve rich, complex animations. Mithril does, however, offer hooks to make life easier in some specific cases where it's traditionally difficult to make animations work.