Text in credits screen was not removed on close

Vocaluxe/Screens/CScreenCredits.cs

@@ -293,6 +293,15 @@ namespace Vocaluxe.Screens
             LogoTimer.Start();
         }
 
+        public override void OnClose()
+        {
+            base.OnClose();
+
+            foreach (CText text in paragraphTexts)
+                text.UnloadTextures();
+            paragraphTexts.Clear();
+        }
+
         public override bool Draw()
         {
             base.Draw();