Allow #ENDSHORT tags

Detect where Preview and ShortEnd came from
Introduce a function to check whether a given GameMode is available for a song

Vocaluxe/Base/CGame.cs

@@ -234,7 +234,7 @@ namespace Vocaluxe.Base
                 for (int beat = _LastEvalBeat + 1; beat <= RecordedBeat; beat++)
                 {
                     if ((_SongQueue.GetCurrentGameMode() == EGameMode.TR_GAMEMODE_MEDLEY && song.Medley.EndBeat == beat) ||
-                        (_SongQueue.GetCurrentGameMode() == EGameMode.TR_GAMEMODE_SHORTSONG && song.ShortEnd == beat))
+                        (_SongQueue.GetCurrentGameMode() == EGameMode.TR_GAMEMODE_SHORTSONG && song.ShortEnd.EndBeat == beat))
                         Players[p].SongFinished = true;
 
                     CSongLine[] lines = song.Notes.GetVoice(Players[p].VoiceNr).Lines;

Vocaluxe/Base/CLog.cs

@@ -118,7 +118,6 @@ namespace Vocaluxe.Base
             if (e != null)
                 errorText += ": " + e;
             _ErrorLog.Add(_NumErrors + ") " + errorText + "\r\n");
-            _ErrorLog.Add(String.Empty);
             if (exit)
                 Environment.Exit(Environment.ExitCode);
         }