Include cause and root cause in FDO exception messages

[jng]

#2005 improved the quality of MgFdoException error messages, but we can do even better

When a MgFdoException is thrown, it only captures the message of the FdoException object, but the FdoException class also includes a cause (FdoException::GetCause()) root cause (FdoException::GetRootCause()) which are lost when re-thrown as a MgFdoException.

The default macros that throw MgFdoException should include the cause and root causes for better quality error messages

[jng]

Fixed trunk (r6832) and 2.4 (r6801)