finished challenge config screen

VocaluxeLib/PartyModes/CPartyMode.cs

@@ -83,6 +83,11 @@ namespace Vocaluxe.PartyModes
             return 0;
         }
 
+        public virtual int GetMaxNumRounds()
+        {
+            return 1;
+        }
+
         public virtual void SetSearchString(string SearchString, bool Visible)
         {
         }

VocaluxeLib/PartyModes/IPartyMode.cs

@@ -64,7 +64,8 @@ namespace Vocaluxe.PartyModes
         int GetMaxPlayer();
         int GetMinPlayer();
         int GetMaxTeams();
-        int GetMinTeams();        
+        int GetMinTeams();
+        int GetMaxNumRounds();
 
         void SetSearchString(string SearchString, bool Visible);