Implemented contexts, optimizations

examples/contexts.php

@@ -0,0 +1,27 @@
+<?php
+
+require_once __DIR__."/../vendor/autoload.php";
+
+use NoccyLabs\Shell\Shell;
+use NoccyLabs\Shell\Context;
+
+$shell = new Shell();
+$shell->addListener("prompt", function ($event, $shell) {
+    $name = $shell->getContextPath();
+    $shell->setPrompt("shell{$name}> ");
+});
+
+$root = new Context();
+$root->addCommand("test", function () {
+    echo "It works!\n";
+});
+$root->addCommand("context", function ($name) {
+    $context = new Context($name);
+    $context->name = $name;
+    return $context;
+});
+$shell->pushContext($root);
+
+
+$shell->run();
+