Split out the javascript protocol interface.

static/sfu.html

@@ -76,6 +76,7 @@
       <div id="peers"></div>
     </div>
 
+    <script src="/protocol.js" defer></script>
     <script src="/sfu.js" defer></script>
   </body>
 </html>

static/tsconfig.json

+{
+    "compilerOptions": {
+        "target": "ES6",
+        "allowJs": true,
+        "checkJs": true,
+        "declaration": true,
+        "emitDeclarationOnly": true,
+        "strictBindCallApply": true
+    },
+    "files": [
+        "protocol.js"
+    ]
+}