Add support for alternate file descriptors

Exposed by `entryType: 'all'` option. Previous use cases are unaffected.

https://github.com/paulmillr/chokidar/issues/192
Not hard bound on line length. If the line becomes much longer than any other line put a line per `||`, i.e.
```js
if ( opts.entryType === ..
  || opts.entryType === ..
   || opts.entryType === ..) {
  [ .. ]
}
```