Rename FrameworkWidgetFactory to ViewFactory

We now deal in views instead of widgets, and the "Framework"
part was redundant. It's also shorter now

src/qtwidgets/Platform_qtwidgets.cpp

@@ -75,7 +75,7 @@ std::shared_ptr<Window> Platform_qtwidgets::windowFromQWindow(QWindow *qwindow)
     return std::shared_ptr<Window>(new Window_qtwidgets(qwindow));
 }
 
-FrameworkWidgetFactory *Platform_qtwidgets::createDefaultFrameworkWidgetFactory()
+ViewFactory *Platform_qtwidgets::createDefaultFrameworkWidgetFactory()
 {
     return new DefaultWidgetFactory_qtwidgets();
 }