Added base files, with the basic ability to add/remove variables from the Runtime.

src/RTEX/Exceptions/Core/UnsupportedInstructionException.php

@@ -0,0 +1,16 @@
+<?php
+
+    namespace RTEX\Exceptions\Core;
+
+    class UnsupportedInstructionException extends \Exception
+    {
+        /**
+         * UnsupportedInstructionException constructor.
+         *
+         * @param string $message
+         */
+        public function __construct(string $message)
+        {
+            parent::__construct($message);
+        }
+    }