/// <summary>
/// Class for encoding and decoding a string to QuotedPrintable
/// RFC 1521 http://www.ietf.org/rfc/rfc1521.txt
/// RFC 2045 http://www.ietf.org/rfc/rfc2045.txt
/// Date: 2006-03-23
/// Author: Kevin Spaun
/// Company: SPAUN Informationstechnik GmbH - http://www.spaun-it.com/
/// Feedback: kspaun@spaun-it.de
/// License: This piece of code comes with no guaranties. You can use it for whatever you want for free.
///
/// Modified by Will Huang ( http://blog.miniasp.com/post/2008/02/14/Quoted-Printable-Encoding-and-Decoding.aspx )
/// Modified at 2008-02-13
///
/// Modified by yongfa365 (http://www.yongfa365.com)
/// Modified at 2008-11-29
/// Modified for MySelf
///
/// </summary>
/// Class for encoding and decoding a string to QuotedPrintable
/// RFC 1521 http://www.ietf.org/rfc/rfc1521.txt
/// RFC 2045 http://www.ietf.org/rfc/rfc2045.txt
/// Date: 2006-03-23
/// Author: Kevin Spaun
/// Company: SPAUN Informationstechnik GmbH - http://www.spaun-it.com/
/// Feedback: kspaun@spaun-it.de
/// License: This piece of code comes with no guaranties. You can use it for whatever you want for free.
///
/// Modified by Will Huang ( http://blog.miniasp.com/post/2008/02/14/Quoted-Printable-Encoding-and-Decoding.aspx )
/// Modified at 2008-02-13
///
/// Modified by yongfa365 (http://www.yongfa365.com)
/// Modified at 2008-11-29
/// Modified for MySelf
///
/// </summary>