On XEngine.ProcessEventHandler(), instead of creating a new CultureInfo on every call use the single one set by Culture.SetCurrentCulture()

This is slightly different in that SetCurrentCulture() does not use overridden settings if the system culture matches en-US but some settings there have been changed.
This is what we want - we do not want to use any system overriden settings.

OpenSim/Region/ScriptEngine/XEngine/XEngine.cs

@@ -1506,8 +1506,7 @@ namespace OpenSim.Region.ScriptEngine.XEngine
         /// <returns></returns>
         private object ProcessEventHandler(object parms)
         {
-            CultureInfo USCulture = new CultureInfo("en-US");
-            Thread.CurrentThread.CurrentCulture = USCulture;
+            Culture.SetCurrentCulture();
 
             IScriptInstance instance = (ScriptInstance) parms;