Change label of "Delete record" button to reflect number of records

Change the label of the "Delete record" button in the Browse Data tab to
"Delete records" when multiple records are selected.

See issue #856.

src/MainWindow.cpp

@@ -462,8 +462,24 @@ void MainWindow::populateTable()
         reconnectSelectionSignals = true;
     ui->dataTable->setModel(m_browseTableModel);
     if(reconnectSelectionSignals)
+    {
         connect(ui->dataTable->selectionModel(), SIGNAL(currentChanged(QModelIndex,QModelIndex)), this, SLOT(dataTableSelectionChanged(QModelIndex)));
 
+        // Lambda function for updating the delete record button to reflect number of selected records
+        connect(ui->dataTable->selectionModel(), &QItemSelectionModel::selectionChanged, [this](const QItemSelection&, const QItemSelection&) {
+            // NOTE: We're assuming here that the selection is always contiguous, i.e. that there are never two selected rows with a non-selected
+            // row in between.
+            int rows = 0;
+            if(ui->dataTable->selectionModel()->selectedIndexes().count())
+                rows = ui->dataTable->selectionModel()->selectedIndexes().last().row() - ui->dataTable->selectionModel()->selectedIndexes().first().row() + 1;
+
+            if(rows > 1)
+                ui->buttonDeleteRecord->setText(tr("Delete records"));
+            else
+                ui->buttonDeleteRecord->setText(tr("Delete record"));
+        });
+    }
+
     // Search stored table settings for this table
     bool storedDataFound = browseTableSettings.contains(tablename);