Minor fix to exit handler, according to jotpio

Author: Hauke Jürgen Mönck

BioTracker/CoreApp/BioTracker/GuiContext.cpp

@@ -86,6 +86,6 @@ void GuiContext::exit() {
     //    delete i;
     //}
 
-	std::exit(0);
     qApp->exit();
+	std::exit(0);
 }