qt: GUI for conflicted transactions

- Exclamation mark icon for conflicted transactions
- Show mouseover status for conflicted transactions as "conflicted"
- Don't show inactive transactions on overview page overview

src/qt/overviewpage.cpp

@@ -175,6 +175,7 @@ void OverviewPage::setWalletModel(WalletModel *model)
         filter->setLimit(NUM_ITEMS);
         filter->setDynamicSortFilter(true);
         filter->setSortRole(Qt::EditRole);
+        filter->setShowInactive(false);
         filter->sort(TransactionTableModel::Status, Qt::DescendingOrder);
 
         ui->listTransactions->setModel(filter);