Added very basic KaitaiStruct implementation

KaitaiStruct.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace Kaitai
+{
+    public class KaitaiStruct
+    {
+        protected KaitaiStream m_io;
+        protected KaitaiStruct m_parent;
+
+        public KaitaiStruct(KaitaiStream _io, KaitaiStruct _parent = null)
+        {
+            m_io = _io;
+            m_parent = _parent;
+        }
+
+        public KaitaiStream _io() { return m_io; }
+        public KaitaiStruct _parent() { return m_parent; }
+    }
+}