Remove  duplicated code ( toSDMM )
Change Send Mail logic for Unix plateform (#FS 1096 )

The default method is now with xdg-email via the local mail service .
Nevertheless, the possibility to send mail directly via SendMail is kept
as a "hiden" option for experienced users.
That  means  there is a parameter  named "SendMailMethod"  set to 0 by
default ; setting it manually to 1 switches to SendMail