Nil - can't locate function name #57

Hi,

I'm trying to use JavaScriptEngineSwitcher for the NiL JS engine as it is the best fit for my use-case, however it seems there is an issue with being able to call functions, with the switcher reporting JavaScriptEngineSwitcher.Core.JsRuntimeException: 'The function with the name 'negate' does not exist.'
yet when I run exactly the same code with Jint it works fine. Is the NiL wrapper not ready for use? The code is from your test cases, as below:

` JsEngineSwitcher engineSwitcher = (JsEngineSwitcher)JsEngineSwitcher.Current;
engineSwitcher.EngineFactories
.AddNiL(new NiLSettings
{
StrictMode = true
})
//.AddJint()
//.AddJurassic()
//.AddMsie(new MsieSettings
//{
// UseEcmaScript5Polyfill = true,
// UseJson2Library = true
//})
//.AddV8()
;

        engineSwitcher.DefaultEngineName = NiLJsEngine.EngineName;
        //engineSwitcher.DefaultEngineName = JintJsEngine.EngineName;

        const string functionCode = @"function negate(value) {
            return -1 * value;
        }";
        using (var engine = JsEngineSwitcher.Current.CreateDefaultEngine())
        {
            try
            {
                engine.Execute(functionCode);
                var result = engine.CallFunction("negate", 22);         //<=== Error here with NiL, function 'negate' not found, OK with Jint
            }
            catch (TimeoutException)
            {
                Console.WriteLine("Timed out!");
            }`