Party NPE fixes. Thx Kerberos :)

L2_GameServer/java/net/sf/l2j/gameserver/model/L2Party.java

@@ -684,7 +684,10 @@ public class L2Party {
 		for (L2PcInstance member : getPartyMembers())
 		{
 			if (member == null)
+			{
+				getPartyMembers().remove(member);
 				continue;
+			}
 			
 			if (member.getLevel() > newLevel)
 				newLevel = member.getLevel();