More examples and tweaks

* Signal dispatch() method now uses own pid as default value
* SharedData now updates checksum cache on set()

examples/signaltraps.php

@@ -0,0 +1,16 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+use NoccyLabs\Ipc\Signal\SignalTrap;
+
+
+
+$trap = new SignalTrap(SIGINT);
+echo "Press ctrl-c...\n";
+
+while (!$trap->isTrapped()) {
+    usleep(10000);
+}
+
+echo "Thanks!\n";