Call dropitem when spawning a quest reward in a network game

This allows the item to appear in the delta sync when a new player joins the game, but does not cause the item to drop for other players on the same level at the time the action occurs due to differences in the way this message is handled.

Source/items.cpp

@@ -3552,6 +3552,10 @@ void SpawnRewardItem(int itemid, Point position)
 	item._iSelFlag = 2;
 	item._iPostDraw = true;
 	item._iIdentified = true;
+
+	if (gbIsMultiplayer) {
+		NetSendCmdPItem(false, CMD_DROPITEM, item.position, item);
+	}
 }
 
 void SpawnMapOfDoom(Point position)