fix(Core/Globals): Frees observer callbacks at destruction (#127)

fixes:#115

Author: JBenda

inkcpp/globals_impl.h

@@ -36,7 +36,12 @@ class globals_impl final
 	// Initializes a new global store from the given story
 	globals_impl(const story_impl*);
 
-	virtual ~globals_impl() {}
+	virtual ~globals_impl()
+	{
+		for (const auto& callback : _callbacks) {
+			delete callback.operation;
+		}
+	}
 
 	snapshot* create_snapshot() const override;
 

inkcpp/include/functional.h

@@ -26,6 +26,7 @@ class callback_base
 {
 public:
 	virtual void call(ink::runtime::value, ink::optional<ink::runtime::value>) = 0;
+	virtual ~callback_base()                                                   = default;
 };
 
 template<typename F>
@@ -313,8 +314,8 @@ class function_array_delegate : public function_base
 				char*       ptr    = buffer;
 				while (*src != '\0')
 					*(ptr++) = *(src++);
-				*ptr            = 0;
-				result          = ink::runtime::value(buffer);
+				*ptr   = 0;
+				result = ink::runtime::value(buffer);
 			}
 			push(stack, result);
 		}