下载页面雏形，修复SpkPopup（改用弹出），添加应用列表固定图标缓存

inc/spkstore.h

@@ -8,9 +8,10 @@
 #include <QtNetwork/QNetworkAccessManager>
 
 #include "spklogging.h"
-#include "spkmainwindow.h"
 #include "spkresource.h"
 
+class SpkMainWindow;
+
 /**
  * @brief SpkStore class is the core of the store client side program, it is constructed first and
  *        handling all processing after the launch. All client side data should be held by it,