Fix crash when copy constructing unhandled packets

Actually this is a workaround: it does not attempt to copy construct
unhandled packets, to avoid a bug in the base class where pointers were
copy constructed without copying the contents.

A proper fix will need refactoring of the packet storage code.

src/qteletextdecoder/levelonepage.h

@@ -36,6 +36,7 @@ public:
 	enum CycleTypeEnum { CTcycles, CTseconds };
 
 	LevelOnePage();
+	// BUG this copy constructor isn't used? Parameter should be LevelOnePage
 	LevelOnePage(const PageBase &other);
 
 	bool isEmpty() const override;