I having issues with `XmlConvert` and `DateTime`.

When converting some string with `XmlConvert.ToDateTime(String)` then convert resulted `DateTime` back to string with `XmlConvert.ToString(DateTime)` and resulting string is **different from the original string**, and depending on local TimeZone.

The following console application code demonstrating the issue:

```
using System;
using System.Xml;

namespace DateTimeXmlConvertTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Original Value\t\t\t\tNew Value");
            Console.WriteLine("--------------\t\t\t\t---------");

            for (int i = -12; i <= 12; i++)
            {
                string sign = i < 0 ? "" : "+";

                string originalString = "2011-10-01T01:18:54.6652000" + sign + i.ToString("D2") + ":00";
                DateTime now = XmlConvert.ToDateTime(originalString);
                string newValue = XmlConvert.ToString(now);
                Console.WriteLine(originalString + "\t" + newValue);
            }
        }
    }
}

```

When running this program on my PC (Windows 7 x64, TimeZone UTC+02:00 with Daylight) i have the following output: 

```
Original Value                          New Value
--------------                          ---------
2011-10-01T01:18:54.6652000-12:00       2011-10-01T16:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-11:00       2011-10-01T15:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-10:00       2011-10-01T14:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-09:00       2011-10-01T13:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-08:00       2011-10-01T12:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-07:00       2011-10-01T11:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-06:00       2011-10-01T10:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-05:00       2011-10-01T09:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-04:00       2011-10-01T08:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-03:00       2011-10-01T07:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-02:00       2011-10-01T06:18:54.6652000+03:00
2011-10-01T01:18:54.6652000-01:00       2011-10-01T05:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+00:00       2011-10-01T04:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+01:00       2011-10-01T03:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+02:00       2011-10-01T02:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+03:00       2011-10-01T01:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+04:00       2011-10-01T00:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+05:00       2011-09-30T23:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+06:00       2011-09-30T22:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+07:00       2011-09-30T21:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+08:00       2011-09-30T20:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+09:00       2011-09-30T19:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+10:00       2011-09-30T18:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+11:00       2011-09-30T17:18:54.6652000+03:00
2011-10-01T01:18:54.6652000+12:00       2011-09-30T16:18:54.6652000+03:00

```

How is it possible when converting to and then from it results with different string?

Is there a way to make it output the original string in this case?

Thanks.