Parameters are not passed to lambda expression

Following example returns... `Unknown identifier 'x' (at index 5).`
``` c#
var target = new Interpreter(InterpreterOptions.Default | InterpreterOptions.LambdaExpressions);
var listInt = target.Eval<List<int>>("list.Select(n => n > x)", new Parameter("list", new[] { 1, 2, 3 }), new Parameter("x", 1));
Assert.AreEqual(new[] { 2, 3 }, listInt);
```