On initial block chain download, show a progress bar

src/qt/clientmodel.h

@@ -36,6 +36,8 @@ public:
 
     /* Return true if core is doing initial block download */
     bool inInitialBlockDownload() const;
+    /* Return conservative estimate of total number of blocks, or 0 if unknown */
+    int getTotalBlocksEstimate() const;
 
     /* Set default address */
     void setAddress(const QString &defaultAddress);