Added in code for Tech Levels using prereqs

and fixed up some kinks of the old system

OpenRA.Mods.RA/ServerTraits/LobbyCommands.cs

@@ -551,6 +551,25 @@ namespace OpenRA.Mods.RA.Server
 						server.LobbyInfo.GlobalSettings.StartingCash = Exts.ParseIntegerInvariant(s);
 						server.SyncLobbyGlobalSettings();
 
+						return true;
+					}},
+				{ "techlevel",
+					s =>
+					{
+						if (!client.IsAdmin)
+						{
+							server.SendOrderTo(conn, "Message", "Only the host can set that option");
+							return true;
+						}
+
+						if (server.Map.Options.TechLevel != null)
+						{
+							server.SendOrderTo(conn, "Message", "Map has disabled Tech configuration");
+							return true;
+						}
+
+						server.LobbyInfo.GlobalSettings.TechLevel = s;
+						server.SyncLobbyInfo();
 						return true;
 					}},
 				{ "kick",