Improve the tag widget to allow us to tab to the next field

If the last key that went in ended a tag and the next key is a tab -
deliver that to the TabWidget instead so we can navigate between input
fields.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/maintab.cpp

@@ -335,6 +335,11 @@ void MainTab::clearEquipment()
 	weightModel->clear();
 }
 
+void MainTab::nextInputField(QKeyEvent *event)
+{
+	keyPressEvent(event);
+}
+
 void MainTab::clearInfo()
 {
 	ui.sacText->clear();