Begin WebSocket support for Broadcast and Player control

modules/React/Stream/WritableStreamInterface.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace React\Stream;
+
+use Evenement\EventEmitterInterface;
+
+/**
+ * @event drain
+ * @event error
+ * @event close
+ * @event pipe
+ */
+interface WritableStreamInterface extends EventEmitterInterface
+{
+    public function isWritable();
+    public function write($data);
+    public function end($data = null);
+    public function close();
+}