Fix sidebar groupby column names error

The visual headings are not reset when the view is reset, for
example after startup. This means the wrong columns are offered
on the activity popup menu for group by.

The resetView() function needed to call columnsChanged() to get
the visual headings reset.

src/RideNavigator.cpp

@@ -124,7 +124,6 @@ RideNavigator::RideNavigator(MainWindow *parent, bool mainwindow) : main(parent)
 
     // we accept drag and drop operations
     setAcceptDrops(true);
-    columnsChanged(); // set visual headings etc
 }
 
 RideNavigator::~RideNavigator()
@@ -261,6 +260,8 @@ RideNavigator::resetView()
 
     // Select the current ride
     rideTreeSelectionChanged();
+
+    columnsChanged();
 }
 
 void RideNavigator::searchStrings(QStringList list)