Expression return type is automatically converted if needed

[Davide Icardi]

It should be possible to force the return type:

        var target = new Interpreter();
        var expressionType = typeof(int);

        var lambda = target.Parse("213.46", expressionType);

        Assert.AreEqual(expressionType, lambda.ReturnType);
        Assert.AreEqual((int)213.46, lambda.Invoke());