some improves and fixes:

1. should get the last loadded aseembly by checking its version instead of reversing.
2. fixed throw an exception when CsScriptRunner run the second time.
3. an argument carried by an UnregisterType called somewhere have had been accidentally removed.

Barotrauma/BarotraumaServer/ServerSource/DebugConsole.cs

@@ -1248,6 +1248,7 @@ namespace Barotrauma
             commands.Add(new Command("cs", "cs: runs a string", (string[] args) =>
             {
                 GameMain.LuaCs.CsScript.Run(string.Join(" ", args));
+                GameMain.LuaCs.RecreateCsScript();
             }));
 
             commands.Add(new Command("reloadlua", "reloads lua", (string[] args) =>