Change worker stuff to use worker-loader

Previously we used webworkify-webpack to make web-workers work. We now
use the worker-loader webpack plugin which is available since webpack 4
to handle workers.

It still doesn't want to connect to the server, but all JS errors in the
dev console are gone. Progress.

app/worker-client.js

@@ -4,8 +4,9 @@ import EventEmitter from 'events'
 import { Writable, PassThrough } from 'stream'
 import toArrayBuffer from 'to-arraybuffer'
 import ByteBuffer from 'bytebuffer'
-import webworkify from 'webworkify'
-import worker from './worker'
+//import work from 'webworkify-webpack'
+//import worker from './worker'
+import Worker from './worker'
 
 /**
  * Creates proxy MumbleClients to a real ones running on a web worker.
@@ -13,7 +14,7 @@ import worker from './worker'
  */
 class WorkerBasedMumbleConnector {
   constructor () {
-    this._worker = webworkify(worker)
+    this._worker = new Worker() //work(require.resolve('./worker'))
     this._worker.addEventListener('message', this._onMessage.bind(this))
     this._reqId = 1
     this._requests = {}

app/worker.js

@@ -3,16 +3,18 @@ import mumbleConnect from 'mumble-client-websocket'
 import toArrayBuffer from 'to-arraybuffer'
 import chunker from 'stream-chunker'
 import Resampler from 'libsamplerate.js'
+import CodecsBrowser from 'mumble-client-codecs-browser'
 
 // Polyfill nested webworkers for https://bugs.chromium.org/p/chromium/issues/detail?id=31666
 import 'subworkers'
 
 // Monkey-patch to allow webworkify-webpack and codecs to work inside of web worker
 /* global URL */
-window.URL = URL
+//if (typeof window === 'undefined')  global.window = {}
+//window.URL = URL
 
 // Using require to ensure ordering relative to monkey-patch above
-let CodecsBrowser = require('mumble-client-codecs-browser')
+//let CodecsBrowser = require('mumble-client-codecs-browser')
 
 export default function (self) {
   let sampleRate