Implements variable usage, tweaks and fixes for variable assignment

src/Evaluator/EvalValues/NumericEvalValue.hpp

@@ -50,6 +50,10 @@ public:
         strs << _value;
         return strs.str();
     }
+
+    EvalValue* Clone() final{
+        return new IntegerEvalValue(_value);
+    }
 };
 
 class FloatEvalValue : public NumericEvalValue{
@@ -74,6 +78,10 @@ public:
         strs << _value;
         return strs.str();
     }
+
+    EvalValue* Clone() final{
+        return new FloatEvalValue(_value);
+    }
 };
 
 #endif //PORYGONLANG_NUMERICEVALVALUE_HPP