expand save_id default value eralier

Set this default value immideately after reading the scenario is
importent because otherwise we might endup settings this value to the
multiplayer players name, which would break carryover. (doing this in at
config loading in game_config would be ok too i think.)

src/saved_game.cpp

@@ -199,6 +199,17 @@ void saved_game::expand_scenario()
 		{
 			this->starting_pos_type_ = STARTINGPOS_SCENARIO;
 			this->starting_pos_ = scenario;
+
+			//Set this default value immideately after reading the scenario is importent because otherwise 
+			//we might endup settings this value to the multiplayer players name, which would break carryover.
+			//(doing this in at config loading in game_config would be ok too i think.)
+			BOOST_FOREACH(config& side, starting_pos_.child_range("side"))
+			{
+				if(side["save_id"].str() == "")
+				{
+					side["save_id"] = side["id"];
+				}
+			}
 		}
 		else
 		{