Added MultiStreamChannel to handle multiple endpoints

examples/multichannels.php

@@ -0,0 +1,39 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+use NoccyLabs\Ipc\Interop\Channel\MultiStreamChannel;
+
+// It really is this simple
+$channel = new MultiStreamChannel();
+
+// Create a child to report back in 3 seconds
+$channel1 = $channel->createClient();
+$pid1 = pcntl_fork();
+if ($pid1 === 0) {
+    sleep(1);
+    echo "child 1 received ".$channel1->receive()."\n";
+    $channel1->send("Hello from child 1");
+    sleep(5);
+    exit;
+}
+
+// Create another child to report back in 4 seconds
+$channel2 = $channel->createClient();
+$pid2 = pcntl_fork();
+if ($pid2 === 0) {
+    sleep(1);
+    echo "child 2 received ".$channel2->receive()."\n";
+    $channel2->send("Hello from child 2");
+    sleep(5);
+    exit;
+}
+
+// Writing to the master works whether any clients have been added
+$channel->send("Hello from master");
+
+// Wait for 5 seconds and dump whatever messages are waiting
+sleep(5);
+while ($msg = $channel->receive()) {
+    echo "master received ".$msg."\n";
+}