* update lerna and lerna-changelog
* Lerna: enable yarn, yarn workspaces [skip ci]
* use older version of Babel since it matches on semver (cannot be the same version)
* install yarn version
* revert node engine change
* update flow
* circle ci on 8
* update lock
* Remove whitespace generation and rely on default printing
Changes to printing:
* Add newline after last empty SwitchCase
* Add newlines around block comments if they are non-flow comments or contain newlines
* Fix a few more fixtures
* Handle arrow function processing via shared API rather than default plugin.
* Fix a few small PR comments.
* Preserve existing spec arrow 'this' rewrites, and support spec in subclass constructors.
While it may appear that this should be done by es2015-function-name,
another way to think about it is that es2015-function-name implements
the naming that javascript engines are supposed to do; and javascript
engines cannot name function expressions that are the object of a
member expression.
* Flip default parameter template
YMMV, I saved ~10b on a 2kb library. Not noticeable at the small scale, by why not do it anyway?
I've (unscientifically) found that flipping the default parameter conditional yields better gzip results. I think this is due to the slightly longer string it can now repeatedly match:
```js
// old
var param = arguments.length <= 0 || void 0 === arguments[0] ? null : arguments[0]
--------------------------------------------------------------^
// new
var param = arguments.length > 1 && void 0 !== arguments[1] ? arguments[1] : null
------------------------------------------------------------------------^
```
Though it's entirely likely gzip will also choose up to the index of the arguments if you many default parameters at different indexes.
* Update tests
