Add TimeSpan Parameter Type

Please add support for TimeSpan parameter types, now we have to use strings and then parse it on code if we could instead just use a TimeSpan as a parameter type and use strings for setting its default value it would be very helpful and make our code much cleaner.

        [Parameter("Time Interval", DefaultValue = "-2.21:41:64")]
        public TimeSpan TimeInterval { get; set; }

And the user should be able to use a time picker to set the value, with an up/down arrow buttons or something like that.