changed challenge party mode song selection (there are still some bugs)

VocaluxeLib/PartyModes/IPartyMode.cs

@@ -28,6 +28,16 @@ namespace Vocaluxe.PartyModes
     /// </summary>
     public struct SelectionOptions
     {
+        /// <summary>
+        /// If != -1, the SongMenu should set the song selection on the provided song index (visible index) if possible
+        /// </summary>
+        public int SongIndex;
+
+        /// <summary>
+        /// If true, the SongMenu should perform the select random song method
+        /// </summary>
+        public bool SelectNextRandomSong;
+
         /// <summary>
         /// Choosing song only by random
         /// </summary>
@@ -69,6 +79,9 @@ namespace Vocaluxe.PartyModes
         EScreens GetMainScreen();
         ScreenSongOptions GetScreenSongOptions();
 
+        void OnSongChange(int SongIndex, ref ScreenSongOptions ScreenSongOptions);
+        void OnCategoryChange(int CategoryIndex, ref ScreenSongOptions ScreenSongOptions);
+
         int GetMaxPlayer();
         int GetMinPlayer();
         int GetMaxTeams();