Fixed MetroDemo.NET45 failure to compile due to missing CleanWindowDemo.xaml (and .xaml.css).
Fixed MetroDemo.NET45 failure to compile due to missing CleanWindowDemo.xaml (and .xaml.css).

psinl/MahApps.Metro,MahApps/MahApps.Metro,batzen/MahApps.Metro,xxMUROxx/MahApps.Metro,Danghor/MahApps.Metro,Evangelink/MahApps.Metro,pfattisc/MahApps.Metro,Jack109/MahApps.Metro,chuuddo/MahApps.Metro,p76984275/MahApps.Metro,jumulr/MahApps.Metro,ye4241/MahApps.Metro