DNN-4755, Allow for more tokens in CoreMessaging E-Mails

As described in the ticket; this will allow for more tokens and therefor
greater flexibility in the core messagin template. It's just adding a
few more tokens with no impact on anything else.
Improved Tokenreplce
Merge remote-tracking branch 'upstream/development' into development
DNN-4891 Added API documentation
DNN-4891 Added API documentation
Merge branch 'EPT's_API_Documentation' of https://github.com/EPTamminga/Dnn.Platform into EPT's_API_Documentation
Merge branch 'EPT's_API_Documentation' of https://github.com/EPTamminga/Dnn.Platform into EPT's_API_Documentation
DNN-4891 Added API documentation
Merge branch 'EPT's_API_Documentation' of https://github.com/EPTamminga/Dnn.Platform into EPT's_API_Documentation
DNN-4891 Added API documentation
Checking out github commit
Revert "Checking out github commit"

This reverts commit fd767ce1876396e440c2dcfe55faea193b681c89.
Revert "Revert "Checking out github commit""

This reverts commit d2c668f25a2667ad8f8e09ed66ecdf39dd417ebd.
Revert "Checking out github commit"

This reverts commit fd767ce1876396e440c2dcfe55faea193b681c89.
Adding comments for sancastle documentation

Adding comments for sancastle documentation from DNN connect 2014
Update Icon.ascx.cs

Added CssClass support
Documented  method:
public static string SendMail(string mailFrom, string mailTo, string cc, string bcc, string replyTo, MailPriority priority, string subject, MailFormat bodyFormat, Encoding bodyEncoding,
                                      string body, string[] attachments, string smtpServer, string smtpAuthentication, string smtpUsername, string smtpPassword, bool smtpEnableSSL)
DNN-5337 - Select an icon set
Ability to exclude link to active tab
1) Fixed documentation for SendEmail method.
2) Added documentation for MailFormat enumeration.
3) Added documentation for MailPriority enumeration.