Use HttpMetaCache to minimize network use.

logic/net/CacheDownload.h

@@ -0,0 +1,34 @@
+#pragma once
+
+#include "Download.h"
+#include "HttpMetaCache.h"
+#include <QFile>
+#include <qcryptographichash.h>
+
+class CacheDownload : public Download
+{
+	Q_OBJECT
+public:
+	MetaEntryPtr m_entry;
+	/// is the saving file already open?
+	bool m_opened_for_saving;
+	/// if saving to file, use the one specified in this string
+	QString m_target_path;
+	/// this is the output file, if any
+	QFile m_output_file;
+	/// the hash-as-you-download
+	QCryptographicHash md5sum;
+public:
+	explicit CacheDownload(QUrl url, MetaEntryPtr entry);
+	
+protected slots:
+	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
+	virtual void downloadError(QNetworkReply::NetworkError error);
+	virtual void downloadFinished();
+	virtual void downloadReadyRead();
+	
+public slots:
+	virtual void start();
+};
+
+typedef QSharedPointer<CacheDownload> CacheDownloadPtr;