Some fixes to allow reload a song from disk

VocaluxeLib/Songs/CSongLoader.cs

@@ -88,6 +88,9 @@ namespace VocaluxeLib.Songs
                 _Song._CalculateMedley = true;
                 _Song.Preview.Source = EDataSource.None;
                 _Song.ShortEnd.Source = EDataSource.None;
+                _Song.Start = 0;
+                _Song.VideoGap = 0;
+                _Song.Preview.StartTime = 0;
 
                 var headerFlags = new EHeaderFlags();
                 StreamReader sr = null;
@@ -761,4 +764,4 @@ namespace VocaluxeLib.Songs
             }
         }
     }
-}
+}