viewer: clear current render queue before creating next queue

Hilariously, the queue was being cleared right after it was being set
thus cancelling the whole operation out. This has now been fixed.

app/widget/viewer/viewer.cpp

@@ -435,6 +435,13 @@ void ViewerWidget::PlayInternal(int speed, bool in_to_out_only)
     return;
   }
 
+  // Kindly tell all viewers to stop caching
+  if (pause_autocache_during_playback_) {
+    foreach (ViewerWidget* viewer, instances_) {
+      viewer->renderer_->ClearVideoQueue();
+    }
+  }
+
   // If the playhead is beyond the end, restart at 0
   if (!in_to_out_only && GetTime() >= GetConnectedNode()->GetLength()) {
     if (speed > 0) {
@@ -464,13 +471,6 @@ void ViewerWidget::PlayInternal(int speed, bool in_to_out_only)
     }
   }
 
-  // Kindly tell all viewers to stop caching
-  if (pause_autocache_during_playback_) {
-    foreach (ViewerWidget* viewer, instances_) {
-      viewer->renderer_->ClearVideoQueue();
-    }
-  }
-
   if (!prequeuing_) {
     FinishPlayPreprocess();
   }