Fix formulas not working on Trends for additional athletes

DataFilter requires an activity selected for formulas
to work even in Trends view, so they fail until
you switch to Activities view and back to Trends.
To avoid this we ensure an activity is selected for
any view selected at startup.
Required for #4718

src/Gui/AbstractView.cpp

@@ -147,6 +147,29 @@ AbstractView::resizeEvent(QResizeEvent *)
     active = false;
 }
 
+void
+AbstractView::notifyViewStateRestored()
+{
+    // lets select the first ride if it has not been set,
+    // currently required to use DataFilter in any view.
+    if (context->ride == nullptr) {
+
+        // lets select the first ride
+        QDateTime now = QDateTime::currentDateTime();
+        for (int i = context->athlete->rideCache->rides().count(); i > 0; --i) {
+            if (context->athlete->rideCache->rides()[i - 1]->dateTime <= now) {
+                context->athlete->selectRideFile(context->athlete->rideCache->rides()[i - 1]->fileName);
+                return;
+            }
+        }
+
+       // otherwise just select the latest ride
+       if (context->athlete->rideCache->rides().count() != 0) {
+           context->athlete->selectRideFile(context->athlete->rideCache->rides().last()->fileName);
+       }
+   }
+}
+
 void
 AbstractView::notifyViewPerspectiveAdded(Perspective* page)
 {

src/Gui/AbstractView.h

@@ -185,11 +185,11 @@ class AbstractView : public QWidget
         bool loaded;
 
         // Support view specific behaviour
-        virtual void notifyViewStateRestored() {}
+        virtual void notifyViewStateRestored();
         virtual void notifyViewPerspectiveAdded(Perspective* page);
         virtual void notifyViewSidebarChanged() {}
-        virtual void setViewSpecificPerspective() {};
-        virtual void notifyViewSplitterMoved() {};
+        virtual void setViewSpecificPerspective() {}
+        virtual void notifyViewSplitterMoved() {}
 
     private slots:
         void onIdle();

src/Gui/Views.cpp

@@ -126,24 +126,6 @@ AnalysisView::isBlank()
     else return true;
 }
 
-void
-AnalysisView::notifyViewStateRestored() {
-
-    // lets select the first ride
-    QDateTime now = QDateTime::currentDateTime();
-    for (int i = context->athlete->rideCache->rides().count(); i > 0; --i) {
-        if (context->athlete->rideCache->rides()[i - 1]->dateTime <= now) {
-            context->athlete->selectRideFile(context->athlete->rideCache->rides()[i - 1]->fileName);
-            break;
-        }
-    }
-
-    // otherwise just the latest
-    if (context->currentRideItem() == NULL && context->athlete->rideCache->rides().count() != 0) {
-        context->athlete->selectRideFile(context->athlete->rideCache->rides().last()->fileName);
-    }
-}
-
 void
 AnalysisView::notifyViewSidebarChanged() {
 

src/Gui/Views.h

@@ -49,7 +49,6 @@ class AnalysisView : public AbstractView
 
     protected:
 
-        void notifyViewStateRestored() override;
         void notifyViewSidebarChanged() override;
         void setViewSpecificPerspective() override;
         void notifyViewSplitterMoved() override;