Improved the context stack

examples/basic.php

@@ -0,0 +1,12 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+use NoccyLabs\Shell\Shell;
+use NoccyLabs\Shell\Context;
+
+
+$myShell = new Shell();
+$myShell->setPrompt("test>");
+$myShell->pushContext(new Context());
+$myShell->run();