added item base class for gold and potions

src/gold.h

@@ -4,10 +4,17 @@
 #include <vector>
 #include "position.h"
 #include "rng.h"
+#include "item.h"
 
-struct gold {
+class gold : public item {
+private:
         int amount;
-        position pos;
+public:
+        gold(const position &pos, const int amount);
+        void print(output *out) const override;
+
+        int get_amount() const;
+        void set_amount(const int new_amount);
 };
 
 typedef std::vector<gold> gold_list;