Add a timer to check for changes in immature or unconfirmed balances,

when these are non-zero. Fixed a minor mem leak.

src/qt/clientmodel.cpp

@@ -18,7 +18,7 @@ ClientModel::ClientModel(OptionsModel *optionsModel, QObject *parent) :
 {
     numBlocksAtStartup = -1;
 
-    pollTimer = new QTimer();
+    pollTimer = new QTimer(this);
     pollTimer->setInterval(MODEL_UPDATE_DELAY);
     pollTimer->start();
     connect(pollTimer, SIGNAL(timeout()), this, SLOT(updateTimer()));