Add created loadOrders function and #pragma once to avoid multiple inclusions

CM2005 Object Oriented Programming/Topic 2/2.5.11/main.cpp

@@ -0,0 +1,10 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include "OrderBookEntry.h"
+#include "MerkelMain.h"
+
+int main()
+{
+  MerkelMain app{};
+}