Reduce includes

src/core/network.h

@@ -24,19 +24,19 @@
 
 #include "config.h"
 
-
 #include <QtGlobal>
 #include <QObject>
 #include <QNetworkAccessManager>
 #include <QAbstractNetworkCache>
-#include <QIODevice>
 #include <QMutex>
 #include <QUrl>
 #include <QNetworkRequest>
-#include <QNetworkReply>
-#include <QNetworkDiskCache>
 #include <QNetworkCacheMetaData>
 
+class QIODevice;
+class QNetworkReply;
+class QNetworkDiskCache;
+
 class NetworkAccessManager : public QNetworkAccessManager {
   Q_OBJECT