Using ToLowerInvariant instead of ToLower (the game works for Turkish players now!)

http://www.moserware.com/2008/02/does-your-code-pass-turkey-test.html

Subsurface/Source/Screens/ServerListScreen.cs

@@ -142,7 +142,7 @@ namespace Barotrauma
                 return;
             }
 
-            if (masterServerData.Substring(0,5).ToLower()=="error")
+            if (masterServerData.Substring(0, 5).ToLowerInvariant() == "error")
             {
                 DebugConsole.ThrowError("Error while connecting to master server ("+masterServerData+")!");