Limit max cover height

Otherwise we can end with huge cover files if the source content has abnormally tall covers. This large files could end exhausting RAM in the iOS client.

YACReaderLibrary/initial_comic_info_extractor.h

@@ -21,6 +21,7 @@ private:
     int _coverPage;
     static bool crash;
     QByteArray _xmlInfoData;
+    void saveCover(const QString &path, const QImage &cover);
 
 public slots:
     void extract();