Rework evaluation to use shared pointers, fix bugs

src/Script.hpp

@@ -19,9 +19,9 @@ using namespace std;
 class Script {
     friend class Evaluator;
 
-    EvalValue* _lastValue;
+    shared_ptr<EvalValue> _lastValue;
     Evaluator* _evaluator;
-    unordered_map<int, EvalValue*>* _scriptVariables;
+    unordered_map<int, shared_ptr<EvalValue>>* _scriptVariables;
 
     explicit Script();
 
@@ -36,7 +36,7 @@ public:
     void Evaluate();
 
     EvalValue* GetLastValue(){
-        return _lastValue;
+        return _lastValue.get();
     };
 
     EvalValue* GetVariable(const string& key);